I could specify the sync target by using rs.syncFrom("[host]:[port]").
And I also could overwrite the sync target.
But I could not reset the target !

RS:SECONDARY> rs.syncFrom(null)
{
        "syncFromRequested" : "",
        "ok" : 0,
        "errmsg" : "could not find member in replica set"
}

Is there the way to reset the sync target ?
Or I have to restart the mongod process ?
(sync target is merely saved on memory in process)