$ sudo apt-get remove criticalmass 

Uninstall criticalmass including dependent package

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

$ sudo apt-get remove --auto-remove criticalmass 

Use Purging criticalmass

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

$ sudo apt-get purge criticalmass 

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 criticalmass 

See Also,