To remove Mate desktop, we will have to install PPA Purge. Open the Terminal and run the following command to install PPA Purge:
sudo apt-get install ppa-purge
Once you have installed PPA Purge, run the following commands to purge the packages installed by Mate PPAs. These commands will remove the installed PPAs and dependencies and uninstall the Mate desktop.
sudo ppa-purge ppa:ubuntu-mate-dev/ppasudo ppa-purge ppa:ubuntu-mate-dev/trusty-mate
Now run the following command to uninstall the remaining Mate packages:
sudo apt-get remove mate-*sudo apt-get autoremove
The above set of commands will uninstall all the downloaded and installed Mate packages from your Ubuntu 14.04 LTS system.