Can't uninstall apps removed from the Appcenter repository

Normally to remove an application, I'd go to the updates tab, select the application and click Uninstall.
I recently installed Pushy (com.github.harisvsulaiman.pushy), which was removed by the store a few days later.
Given that it does no longer appear in Appcenter, it is now impossible to remove it, apart from using apt.

It seems that this becomes a problem if for whatever reason an app is removed from the repo (or the repo itself is removed), as then there is no graphical way to uninstall the app.