Is it your house or are you renting?

If it is your house give them an eviction notice, it is usually 30 days (at least where I live).

If your renting talk to your landlord, they can evict them.

If neither of these work call the police and tell them the story and say you want them gone.

Just tell someone. That's the best you can do, you don't want to get into trouble for what your roommates doing.

The question is what is the roommates standing. Are you co-owners or did you both sign a rental lease or what? This will dictate what you do.

Generally, if you know someone is doing something illegal you report it to the police.