You can uninstall or removes an installed freespace2-launcher-wxlauncher package itself from Ubuntu 16.04 LTS (Xenial Xerus) through the terminal,
$ sudo apt-get remove freespace2-launcher-wxlauncher
If you would like to remove freespace2-launcher-wxlauncher and it's dependent packages which are no longer needed from Ubuntu,
$ sudo apt-get remove --auto-remove freespace2-launcher-wxlauncher
If you use with purge options to freespace2-launcher-wxlauncher package all the configuration and dependent packages will be removed.
$ sudo apt-get purge freespace2-launcher-wxlauncher
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 freespace2-launcher-wxlauncher