$ sudo apt-get remove os8 

Uninstall os8 including dependent package

If you would like to remove os8 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove os8 

Use Purging os8

If you use with purge options to os8 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge os8 

If you use purge options along with auto remove, will be removed everything regarding the package, It's really useful when you want to reinstall again.

$ sudo apt-get purge --auto-remove os8 

See Also,