If you have a version of the Guest Additions installed on your virtual machine and wish to remove it without installing new ones, you can do so by inserting the Guest Additions CD image into the virtual CD-ROM drive as described above. Then run the installer for the current Guest Additions with the uninstall parameter from the path that the CD image is mounted on in the guest, as follows:

sh ./VBoxLinuxAdditions.run uninstall

While this will normally work without issues, you may need to do some manual cleanup of the guest in some cases, especially of the XFree86Config or xorg.conf file. In particular, if the Additions version installed or the guest operating system were very old, or if you made your own changes to the Guest Additions setup after you installed them.

You can uninstall the Additions as follows:

/opt/VBoxGuestAdditions-version/uninstall.sh

Replace /opt/VBoxGuestAdditions-version with the correct Guest Additions installation directory.