Uninstall just vagrant

This will remove just the vagrant package itself.

sudo apt-get remove vagrant

Uninstall vagrant and its dependencies

To remove the vagrant package and any other dependant package which are no longer needed from Ubuntu.

sudo apt-get remove --auto-remove vagrant

Purging vagrant (your config/data too)

If you also want to delete your local/config files for vagrant then this will work.

sudo apt-get purge vagrant

To delete configuration and/or data files of vagrant and it's dependencies from Ubuntu then execute.

sudo apt-get purge --auto-remove vagrant