Myself and two other people are renting a townhouse in Virginia. None of us have signed a lease. We all moved in when the previous renter moved out, and we haven't signed anything. Now, I would like to get rid of my other two roommates, but I don't know how. Should I just contact the landlord?

Yes, you need to contact the landlord and sign a lease. Make sure that the lease is back dated to the month that you moved in. Not signing a lease just opens yourself up to being able to be sued by the landlord. Also pay your rent via check or money order, and keep the stub. If you have to pay in cash make sure you get a receipt.

You have no right to evict your roommates, only the landlord can evict. Why don't you just move out?

If you do move out here are a couple things to keep in mind:
Make sure you give 30 days notice, IN WRITING! Make sure that your written notice says something like " Effective MM/DD/YYY: I, YOUR NAME, can not be held responsible for rent or utilities. " Most important, make sure your other roommates sign it! Give them copies, and keep the original for yourself.