$ sudo apt-get remove gcj-jdk 

Uninstall gcj-jdk including dependent package

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

$ sudo apt-get remove --auto-remove gcj-jdk 

Use Purging gcj-jdk

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

$ sudo apt-get purge gcj-jdk 

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 gcj-jdk 

See Also,