Ik vond met reomove-paa ubuntu o.a.
Use the --remove flag, similar to how the PPA was added:
sudo add-apt-repository --remove ppa:whatever/ppa
As a safer alternative, you can install ppa-purge:
sudo apt-get install ppa-purge
And then remove the PPA, downgrading gracefully packages it provided to packages provided by official repositories:
sudo ppa-purge ppa_name
Anyway, this won't uninstall packages that were on the PPA but not on tha official repositories. If you want to remove them, you should tell it to apt:
sudo apt-get purge package_name
You can also remove PPAs by deleting the .list files from /etc/apt/sources.list.d directory.