I think I may have run across a bug but may be pilot error or a “feature” 
The use-case involves both a Harmony Remote and a Cell Phone (Android) Presence Detector. Adding each and setting them up is fine and their day to day use is fine. The condition surfaces when trying to remove the cell phone from SmartThings. As we all know, this can’t happen if there are smart apps that still make use of the device being removed. However, my Harmony remote does not make use of the Cell Phone/Presence Detector in any smart apps or anywhere else that I am aware of. Yet I cannot remove the cell phone/presence detector unless the Harmony remote is completely removed, which means removing all the other smart apps that are associated with that device and then setting them up again when adding it back. Is there something I’m missing or is this a bug?