$ sudo apt-get remove gdb-source 

Uninstall gdb-source including dependent package

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

$ sudo apt-get remove --auto-remove gdb-source 

Use Purging gdb-source

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

$ sudo apt-get purge gdb-source 

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 gdb-source 

See Also,