You can remove a PPA added in Ubutnu and/or it’s derivatives simply. Just add –remove to the command that you used for adding the PPA. I’ll show you how. Suppose, gnome3-team/ppa is the PPA for GNOME3 Team. Now you’ve added this and want to remove it, anyway. The command should be like the following:
sudo apt-add-repository –remove ppa:gnome3-team/ppa
Now update your repositories and that’s it.
sudo apt-get update