I don't know if you own the house or are renting and if his name is on anything or not.
You will need to check with your state's 'tenants law' as to getting him removed. In some states you actually have to give him an eviction notice, even if his name is NOT on anything, but just by the fact that said person has lived at that address for X amount of time. See what is required legally to get him out.
Or if you and your child are leaving, then go ahead, get your new digs set up and then have the 'moving folks' (ie anyone that is going to help you or a moving company) come and move out your possessions.
He isn't going to hear you, he isn't going to believe you, you don't need to forewarn him, just do what you need to do for you and your child.
If he were a 'normal' person, yes it would be courteous to tell him of your plans, however, you are NOT dealing with 'normal.' You are dealing with a very sick individual that is living in a very false reality.
DO what you NEED to do for you and your child!
Love and hugs,