Some people clean up their ubuntu system in command line by apt-get autoclean,autoremove command,but I’d like to use GUI tool because there would be some packages I want not to remove and I cannot choose which to remove and which not to remove in command.BleachBit is a special GUI tool to clean up useless package,cache and free disk space.
Ubuntu-Tweak can also do this work which list useless packages,configure file,cache and kernel and you can choose which to delete.

Open up Ubuntu-Tweak,in left of the window go to Applications->Package Cleaner,click the four buttons in right and it will list useless files in box.Select which you want to delete and click Cleanup


See how to install ubuntu-tweak: