system preferences is busy
hey!! so I just got my MacBook Air less than a week ago, and I had created a separate login for my sister to use, but she then just got her own computer. I went in to setting, hit users and groups, and was attempting to delete her login. it was letting me, but now its been over 12 hours, and its still saying "deleting account.." I now can't close it because 'system preferences is busy" if there's anyway I can restart my computer without having to get into the main settings because like I said before, it won't let me get there. or if there is anyway I can make it finish. I even tried letting my MacBook die completely before I turned it on again, only to see its still there. somebody please help, I don't know what I did.
MacBook Air 13″, macOS 10.15