You can uninstall or removes an installed gr-air-modes package itself from Ubuntu 16.04 LTS (Xenial Xerus) through the terminal,
$ sudo apt-get remove gr-air-modes
If you would like to remove gr-air-modes and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove gr-air-modes
If you use with purge options to gr-air-modes package all the configuration and dependent packages will be removed.
$ sudo apt-get purge gr-air-modes
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 gr-air-modes