You'll want to use the tool ppa-purge from the package ppa-purge to remove the PPAs you have enabled and revert back to the official versions of the package which the PPAs provide. Here's an example from the man page.
sudo ppa-purge -o sarvatt -p xorg-testing will remove https://launchpad.net/~sarvatt/+archive/xorg-testing ** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Incomplete ** Summary changed: - Can’t upgrade from 14.04 to 16.04 + Can’t upgrade from 14.04 to 16.04 with PPAs enabled -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1825564 Title: Can’t upgrade from 14.04 to 16.04 with PPAs enabled To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1825564/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs