All you have to do is type in BleachBit in Ubuntu Software Center to install BleachBit with USC wizard.

When you are done installing. go to Applications > System Tools> BleachBit.

The root shortcut for BleachBit deletes junk files related to the root user and directories, and the regular BleachBit shortcut deletes junk files related to applications like Firefox, WineHQ, etc.

When I ran a BleachBit Root scan, it found 386.1 MB of Junk/Temporary files.
When I ran a BleachBit Regular scan, it found 438.6 MB  Junk/Temporary files.

Using BleachBit also protects your privacy since it deletes your temporary internet files, tracking cookies, and your web browsers history.