$ sudo apt-get remove geant321 

Uninstall geant321 including dependent package

If you would like to remove geant321 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove geant321 

Use Purging geant321

If you use with purge options to geant321 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge geant321 

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 geant321 

See Also,