1. ppa-purge ppa:graphics-d
  2. rivers-ubuntu-ppa-yakkety
  3. Updating packages lists
  4. PPA to be removed: ppa:graphics-drivers-ubuntu-ppa-yakkety
  5. ppa:graphics-drivers-ubuntu-ppa-yakkety
  6. Warning: Could not find package list for PPA:
  7. ppa:graphics-drivers-ubuntu-ppa-yakkety ppa:graphics-drivers-ubuntu-ppa-yakkety