You should check the MSysReplicas table to see exactly how many replicas there are with the path/filename/UNC path that you're trying to delete. In certain circumstances I've never figured out, it takes as many attempted synchs to completely delete a replica from the list as there are records for that replica in MSysReplicas. That is, the failed synch doesn't delete all the replicas with the same name, it just deletes one of them each time.
For instance, if your dead replica is called "C:\MyDeadReplica.mdb" on machine MYPC, you might find 10 records in MSysReploicas with that name/path on that particular PC. That means you have to attempt the synch 10 times.
Also, different replicas may have different records of different replicas in them, and you may need to do this from multiple records.
It's something of a mystery, I've found, but repeated synching with the dead replica will eventually delete all the replicas. You may need to synch around your full replica set for it to take effect, and it may also require a compact before it fully "takes."
Last of all, DON'T DO THIS AGAIN. Use the TSI Synchronizer and do a legal MoveReplica command, instead. Creating dead replicas endangers the health and reliability of your replica set and that's something you never want to do on purpose.