How to make a USB stick with iso9660 filesystem writeable again?

Question

I used the Startup Disk Creator to make a bootable USB stick and now it can only be mounted read-only.

Output of sudo mount /media/user/Volume_Label/ -o remount,rw:

mount: cannot remount /dev/sdb1 read-write, is write-protected

Output of mount command:

/dev/sdb1 on /media/user/Volume_Label type iso9660 (ro,nosuid,nodev,relatime,uid=1000,gid=1000,iocharset=utf8,mode=0400,dmode=0500,uhelper=udisks2)

Output of dmesg command:

[108080.964308]  sdb: sdb1 sdb2
[108080.966929] sd 12:0:0:0: [sdb] Attached SCSI removable disk
[108093.023957] ISO 9660 Extensions: Microsoft Joliet Level 3
[108093.026207] ISO 9660 Extensions: Microsoft Joliet Level 3
[108093.027453] ISO 9660 Extensions: RRIP_1991A

How do I make this USB stick writeable again?

Solution

You can't write to a medium formatted with the ISO 9660 filesystem because it is a filesystem designed for CD's/DVD's and therefore it isn't capable of write operations.
ISO 13490 is a extension of ISO 9660 which adds write support.

Wikipedia excerpt:

Since ISO 9660 is by design a read-only, pre-mastered file system, all the data has to be written in one go or "session" to the medium. Once written, there is no provision for altering the stored content. ISO 13490 was created to allow adding more files to a writeable disc such as CD-R in multiple sessions.

To erase the USB stick and format it with a write supporting filesystem you can use sudo mkfs.vfat -I /dev/sdb (the -I tells mkfs to utilize the entire volume). Also refer to my answer here.