There is no bulk delete on IP, but when you are doing a discovery, those stays in the discovery queue and you have to activly select them for move to the config yourself. So no worries, the discovery queue can be as large as you want without affecting the license count.
Is there any way to delete devices that have the same IP address? I have hundreds of objects that are the same because when we do a discovery, it adds devices that already exist. It is eating up my licenses and finding & deleting manually is too tedius.