Get rid of ghost projects in Gitlab

I have two projects in my Gitlab instance which shows up in ‘explore projects’ tab but are not really existing in the instance. I cannot find them under Admin → projects page or the user who is the owner cannot access them. There are some ToDo tasks which are associated with these projects which cannot be cleared. Admins including the project owners cannot access project page, it always gives 404 error. (The owners of the project said these ghost projects appeared from some backup-restore action they did some years back)I’m wondering how I can get rid of such projects completely from the instance (They affect my upgrade plan to version 14 - as they use legacy storage)
Any help will be much appreciated.

Thank you.