This is a vendor specific implementation. Mostly, whenever admin state is made down, first the Cell Stop takes place. During this state, eNB either releases UE or Hands over to other eNB, if UE gets a good neighbour signal. The RF doesn't go down immediately, rather gradually. So, RRM does a cell re-configuration and some params are modified according to the cell stop state and they are broadcasted in SI messages.
Followed by, Cell Delete state is triggered. In this state, eNB kills all the processes and the RF also goes down completely. So, no one can know about the existence of the cell anymore.
