When I hard wire my simply safe outdoor camera do I insert the battery or leave it out?

When I hard wire my simply safe outdoor camera do I insert the battery or leave it out?

Like captain said they are better and I have one on power cord and the other 4 or on solar and never have to worry and the driveway that has solar gets hits at least 50 times a day and never goes below 95%. Even with solar or power cord leave battery