$ sudo apt-get remove libgcj15 

Uninstall libgcj15 including dependent package

If you would like to remove libgcj15 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove libgcj15 

Use Purging libgcj15

If you use with purge options to libgcj15 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge libgcj15 

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 libgcj15 

See Also,