You don't have any right to remove her. If you are JTWROS with your father, then he, like you, is an owner of the property. Any owner may let any person he likes live on or in the property; so just as you could move in your significant other, for example, he can move in this woman. You each, as joint tenants, have equal rights to use, occupy, possess, and allow others to use, occupy, and posses the property. One co-owner cannot evict the other co-owner's guests.