@Vacuum,

Unfortunately, there is no way to remove a room that was created. I have already passed this feedback along to the developers for consideration, or to see if there is a way to 'hide' the room. My niece left our fridge open on my home's intial mapping XD

For now, when you first create your map - you can try to cover any areas that are causing problems, however the best solution is to use no-go/virtual walls to prevent the vacuum from trying to go into those areas. You can then also set your cleaning preference to leave out a room from whole-home cleans.