No way to deselect repo language choice (BB-5916)

There is currently no way to deselect the language choice for a repo in the admin section. The drop down will only allow you to select a different language even though you can create a repo with no language selected. This could be useful for when a project changes and no longer uses a single language.

A //'None'// option or a little x like on the component drop-down on the issue tracker would be appreciated