Error doing push force for hidden ref

I have run found that I have old keys in my code but I have to remove them even though they are expired.

I did a clone mirror of my project and then used BFG to clean up the code but when I try to push the changed code back to gitlab, I get errors like
! [remote rejected] refs/merge-requests/1/head → refs/merge-requests/1/head (deny updating a hidden ref)

gitleaks reports that the old keys are still in the repository. How do I get rid of the hidden ref’s so that I can push the code back to gitlab?