How to revert to factory settings?

Solution 1:

AFAIK, there is no way to "reset" Ubuntu. You can't even do that on Windows 7 unless there is an OEM-provided recovery partition...

Just burn the latest ISO to a DVD and reinstall.

Easiest way, plus you'll get 16.04's new features :)

Recently there is appeared a new tool to get this. Its name is Resetter, and you can find it here on Github.

With Resetter you can completely clean up your system or choose what you want to remove.

How to install (nowadays) it's via the newest deb file:

sudo dpkg -i resetter_0.0.?-beta_all.deb

Then you can run it directly:

resetter

And now choose Automatic Reset or Custom Reset. You'll be asked for a new administrator user and password (don't forget it)