Can't uninstall Python 3.6

Question

I want to uninstall my 3.6 version without touching the original 3.5 version. So I ran

sudo apt-get remove python3.6

but the output was:

E: Unable to locate package python3.6
E: Couldn't find any package by glob 'python3.6'
E: Couldn't find any package by regex 'python3.6'

$ dpkg -l python3.6
dpkg-query: no packages found matching python3.6

$ dpkg -l python3
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name           Version      Architecture Description
+++-==============-============-============-=================================
ii  python3        3.5.1-3      amd64        interactive high-level object-ori

$ apt-cache policy python3
python3:
  Installed: 3.5.1-3
  Candidate: 3.5.1-3
  Version table:
 *** 3.5.1-3 500
        500 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

My goal is described in Ubuntu 16.04 : Can't seem to make numpy work in python 3.6.5 but it works fine in python 2.7.12. I'm unable to make my code run in neither of python2.7, python3.5, python 3.6. I'm fine with whatever Python version so long as I'm able to run my code.

$ type python
python is hashed (/usr/bin/python)
$ type python3
python3 is hashed (/usr/local/bin/python3)
$ type python3.6
python3.6 is hashed (/usr/local/bin/python3.6)

$ apt list --installed 'python*'
Listing... Done
python/xenial-updates,now 2.7.12-1~16.04 amd64 [installed]
python-all/xenial-updates,now 2.7.12-1~16.04 amd64 [installed,automatic]
python-all-dev/xenial-updates,now 2.7.12-1~16.04 amd64 [installed,automatic]
python-apt-common/xenial-updates,xenial-updates,now 1.1.0~beta1ubuntu0.16.04.1 all [installed]
python-crypto/xenial-updates,xenial-security,now 2.6.1-6ubuntu0.16.04.3 amd64 [installed]
python-dbus/xenial,now 1.2.0-3 amd64 [installed,automatic]
python-dev/xenial-updates,now 2.7.12-1~16.04 amd64 [installed,automatic]
python-gi/xenial,now 3.20.0-0ubuntu1 amd64 [installed,automatic]
python-ldb/xenial,now 2:1.1.24-1ubuntu3 amd64 [installed]
python-minimal/xenial-updates,now 2.7.12-1~16.04 amd64 [installed]
python-numpy/xenial,now 1:1.11.0-1ubuntu1 amd64 [installed]
python-pip/xenial-updates,xenial-updates,now 8.1.1-2ubuntu0.4 all [installed]
python-pip-whl/xenial-updates,xenial-updates,now 8.1.1-2ubuntu0.4 all [installed,automatic]
python-pkg-resources/xenial,xenial,now 20.7.0-1 all [installed,automatic]
python-pyatspi/xenial,xenial,now 2.18.0+dfsg-3 all [installed,automatic]
python-samba/xenial-updates,xenial-security,now 2:4.3.11+dfsg-0ubuntu0.16.04.13 amd64 [installed]
python-setuptools/xenial,xenial,now 20.7.0-1 all [installed,automatic]
python-talloc/xenial,now 2.1.5-2 amd64 [installed]
python-tdb/xenial,now 1.3.8-2 amd64 [installed]
python-wheel/xenial,xenial,now 0.29.0-1 all [installed,automatic]
python2.7/xenial-updates,now 2.7.12-1ubuntu0~16.04.3 amd64 [installed]
python2.7-dev/xenial-updates,now 2.7.12-1ubuntu0~16.04.3 amd64 [installed,automatic]
python2.7-minimal/xenial-updates,now 2.7.12-1ubuntu0~16.04.3 amd64 [installed]
python3/xenial,now 3.5.1-3 amd64 [installed]
python3-apport/xenial-updates,xenial-updates,now 2.20.1-0ubuntu2.17 all [installed]
python3-apt/xenial-updates,now 1.1.0~beta1ubuntu0.16.04.1 amd64 [installed]
python3-aptdaemon/xenial,xenial,now 1.1.1+bzr982-0ubuntu14 all [installed]
python3-aptdaemon.gtk3widgets/xenial,xenial,now 1.1.1+bzr982-0ubuntu14 all [installed]
python3-aptdaemon.pkcompat/xenial,xenial,now 1.1.1+bzr982-0ubuntu14 all [installed]
python3-blinker/xenial,xenial,now 1.3.dfsg2-1build1 all [installed]
python3-brlapi/xenial-updates,now 5.3.1-2ubuntu2.1 amd64 [installed]
python3-bs4/xenial,xenial,now 4.4.1-1 all [installed]
python3-cairo/xenial,now 1.10.0+dfsg-5build1 amd64 [installed]
python3-cffi-backend/xenial,now 1.5.2-1ubuntu1 amd64 [installed]
python3-chardet/xenial,xenial,now 2.3.0-2 all [installed]
python3-checkbox-support/xenial,xenial,now 0.22-1 all [installed]
python3-commandnotfound/xenial-updates,xenial-updates,now 0.3ubuntu16.04.2 all [installed]
python3-cryptography/xenial-updates,xenial-security,now 1.2.3-1ubuntu0.1 amd64 [installed]
python3-cups/xenial,now 1.9.73-0ubuntu2 amd64 [installed]
python3-cupshelpers/xenial,xenial,now 1.5.7+20160212-0ubuntu2 all [installed]
python3-dateutil/xenial,xenial,now 2.4.2-1 all [installed,automatic]
python3-dbus/xenial,now 1.2.0-3 amd64 [installed]
python3-debian/xenial,xenial,now 0.1.27ubuntu2 all [installed]
python3-defer/xenial,xenial,now 1.0.6-2build1 all [installed]
python3-dev/xenial,now 3.5.1-3 amd64 [installed,automatic]
python3-distupgrade/xenial-updates,xenial-updates,xenial-security,xenial-security,now 1:16.04.25 all [installed]
python3-feedparser/xenial,xenial,now 5.1.3-3build1 all [installed]
python3-gdbm/xenial,now 3.5.1-1 amd64 [installed]
python3-gi/xenial,now 3.20.0-0ubuntu1 amd64 [installed]
python3-gi-cairo/xenial,now 3.20.0-0ubuntu1 amd64 [installed]
python3-guacamole/xenial,xenial,now 0.9.2-1 all [installed]
python3-html5lib/xenial,xenial,now 0.999-4 all [installed]
python3-httplib2/xenial,xenial,now 0.9.1+dfsg-1 all [installed]
python3-icu/xenial,now 1.9.2-2build1 amd64 [installed]
python3-idna/xenial,xenial,now 2.0-3 all [installed]
python3-jinja2/xenial,xenial,now 2.8-1 all [installed]
python3-jwt/xenial-updates,xenial-updates,xenial-security,xenial-security,now 1.3.0-1ubuntu0.1 all [installed]
python3-louis/xenial-updates,xenial-updates,xenial-security,xenial-security,now 2.6.4-2ubuntu0.1 all [installed]
python3-lxml/xenial,now 3.5.0-1build1 amd64 [installed]
python3-mako/xenial,xenial,now 1.0.3+ds1-1ubuntu1 all [installed]
python3-markupsafe/xenial,now 0.23-2build2 amd64 [installed]
python3-minimal/xenial,now 3.5.1-3 amd64 [installed]
python3-oauthlib/xenial,xenial,now 1.0.3-1 all [installed]
python3-padme/xenial,xenial,now 1.1.1-2 all [installed]
python3-pam/xenial,now 0.4.2-13.2ubuntu2 amd64 [installed]
python3-pexpect/xenial,xenial,now 4.0.1-1 all [installed]
python3-pil/xenial-updates,xenial-security,now 3.1.2-0ubuntu1.1 amd64 [installed]
python3-pip/xenial-updates,xenial-updates,now 8.1.1-2ubuntu0.4 all [installed]
python3-pkg-resources/xenial,xenial,now 20.7.0-1 all [installed]
python3-plainbox/xenial,xenial,now 0.25-1 all [installed]
python3-problem-report/xenial-updates,xenial-updates,now 2.20.1-0ubuntu2.17 all [installed]
python3-ptyprocess/xenial,xenial,now 0.5-1 all [installed]
python3-pyasn1/xenial,xenial,now 0.1.9-1 all [installed]
python3-pyatspi/xenial,xenial,now 2.18.0+dfsg-3 all [installed]
python3-pycurl/xenial,now 7.43.0-1ubuntu1 amd64 [installed]
python3-pyparsing/xenial-updates,xenial-updates,now 2.0.3+dfsg1-1ubuntu0.1 all [installed]
python3-renderpm/xenial,now 3.3.0-1 amd64 [installed]
python3-reportlab/xenial,xenial,now 3.3.0-1 all [installed]
python3-reportlab-accel/xenial,now 3.3.0-1 amd64 [installed]
python3-requests/xenial,xenial,now 2.9.1-3 all [installed]
python3-setuptools/xenial,xenial,now 20.7.0-1 all [installed,automatic]
python3-six/xenial,xenial,now 1.10.0-3 all [installed]
python3-software-properties/xenial-updates,xenial-updates,now 0.96.20.7 all [installed]
python3-speechd/xenial,xenial,now 0.8.3-1ubuntu3 all [installed]
python3-systemd/xenial,now 231-2build1 amd64 [installed]
python3-tk/xenial,now 3.5.1-1 amd64 [installed]
python3-uno/xenial-updates,xenial-security,now 1:5.1.6~rc2-0ubuntu1~xenial3 amd64 [installed]
python3-update-manager/xenial-updates,xenial-updates,xenial-security,xenial-security,now 1:16.04.12 all [installed]
python3-urllib3/xenial-updates,xenial-updates,now 1.13.1-2ubuntu0.16.04.1 all [installed]
python3-wheel/xenial,xenial,now 0.29.0-1 all [installed,automatic]
python3-xdg/xenial,xenial,now 0.25-4 all [installed]
python3-xkit/xenial,xenial,now 0.5.0ubuntu2 all [installed]
python3-xlsxwriter/xenial,xenial,now 0.7.3-1 all [installed]
python3.5/xenial-updates,xenial-security,now 3.5.2-2ubuntu0~16.04.4 amd64 [installed]
python3.5-dev/xenial-updates,xenial-security,now 3.5.2-2ubuntu0~16.04.4 amd64 [installed,automatic]
python3.5-minimal/xenial-updates,xenial-security,now 3.5.2-2ubuntu0~16.04.4 amd64 [installed]

Solution

Your python3 and python3.6 binaries¹ are installed in /usr/local/bin which is not the default location and dpkg (or APT) does not know about them. So they weren’t most likely installed by dpkg or APT. To uninstall them, just remove them from the /usr/local/bin folder.

Preliminary check

I recommend to rename them first:

sudo mv /usr/local/bin/python3 /usr/local/bin/python3.bak
sudo mv /usr/local/bin/python3.6 /usr/local/bin/python3.6.bak

Then check whether the version installed by APT kicks in when you run python3:

python3 --version # expected output: Python 3.5.2

If this check succeeds, you can safely remove the files /usr/local/bin/python3.bak and /usr/local/bin/python3.6.bak.

---

¹ In fact, one file might be a symlink to the other.

Comments

[solsTiCe]

Why do you want to uninstall python3 ? You can have both installed. Just specify the interpreter to use on the command-line aka python2 or in the shebang with #!/usr/bin/python2

[goalpost]

I am now able to run my code using python3.5 in the terminal :-) Still not able to figure out how to run it using python3 OR python though.

[user535733]

The answer depends upon what method you used to install Py3.6, go back through your notes (or memory). If you can link to the original instructions you followed, even better. For example, apt can remove only deb packages - it cannot see pip or flatpack or tar, etc.

[Melebius]

@SHREYASHANARASE Thank you for the added information. It’s strange that dpkg show python3 to be the version 3.6.5 while apt thinks it’s python3/xenial,now 3.5.1-3 amd64. Could you add the output of apt-cache policy python3 to your question? BTW is your dpkg -l output exactly what you reported? I get another format using the same command on Ubuntu 16.04: ii python3 3.5.1-3 amd64 interactive high-level object-oriented lang

[Melebius]

Welcome to Ask Ubuntu and thank you for the tip! However, I am afraid your answer won’t work in this case. When OP cannot complete apt-get remove, then he much likely cannot complete apt purge which includes apt-get remove.

[goalpost]

The output is : Python 3.5.2 . Can I remove these files /usr/local/bin/python3.bak and /usr/local/bin/python3.6.bak now? I only want to uninstall python 3.6 and restore everything to normal. So that maybe at a later point I can install python 3.6 using the recommended way, which is what ?

[Melebius]

Yes, I can confirm, in my case it also returns Python 3.5.2, although the package version is 3.5.1-3. So it seems to be the 16.04 default. To get Python 3.6 on Ubuntu 16.04, you should use PPA: askubuntu.com/q/865554/250300