$ sudo apt-get remove pgadmin3 

Uninstall pgadmin3 including dependent package

If you would like to remove pgadmin3 and it's dependent packages which are no longer needed from Ubuntu,

$ sudo apt-get remove --auto-remove pgadmin3 

Use Purging pgadmin3

If you use with purge options to pgadmin3 package all the configuration and dependent packages will be removed.

$ sudo apt-get purge pgadmin3 

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 pgadmin3 

See Also,