If you're looking to Pause or Stop Replication, go to the [Replication] menu option.
You will be presented with a list of VMs that have replication set up. Simply click on the spanner icon next to the VM and choose whether you'd like to [Pause] or [Stop] replication.
Pausing replication will simply cease replicating that VM until you [Resume] it manually.
Stopping replication will completely remove the VMs replication settings and will stop being replicated until you reconfigure it.