How to change pending_delete status

I'm running a self-hosted GitLab CE 8.12.0

After I deleted a project in a group, I tried to fork a project from another group with the same name but failed with error: Name has already been taken.

I tried several times without success. I even deleted the physical repo at server, again the fork still failed.

Is there any other way that I should do to resolve this?

I also found out that there's a flag called pending_status that may have caused this.

Can I change this status?

Thanks and Regards.