How to delete a project open by another user

Hi,

I have several old projects which is copies I made as back-ups, these copies are no longer used, when I initiate the delete project process I receive a pop up error that reads, cannot delete this projects, project open by another user.

However when I open the project and view project users, I am the only user, how do I work around this to delete these old projects. Note, this is on a standalone version and not database.