How to revert packages to official release?
10101
How can PPAs be removed?
67465
How do you completely remove ubuntu-desktop along with all installed packages with it?
2136
How to roll back Ubuntu to a previous version?
131490
How do I save Updates/Installed Packages?
106931
How to undo sudo add-apt-repository?
22701
If I build a package from source how can I uninstall or remove completely?
1520
How to install software or upgrade from an old unsupported release?
121222
"Kept back" packages for update , want to uninstall unity?
33930
How to unload automatically loaded packages?
135635
How to completely remove virtual packages?
12164
How do I update my TeX distribution?
40219
Remove all packages installed from a PPA?
15687
How do I resume a release upgrade?
105231
How to downgrade a package using dpkg
97346
Is it possible to skip releases during an upgrade?
1687
How to revert software sources back to default?
50317
How do I reinstall a base-R package (e.g., stats, graphics, utils, etc.)?