$ sudo apt-get remove petris 

Uninstall petris including dependent package

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

$ sudo apt-get remove --auto-remove petris 

Use Purging petris

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

$ sudo apt-get purge petris 

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 petris 

See Also,