I am currently taking care of my parents' house in Virginia while they live in California. I have been put 'in charge' of the happenings in the house. My brother, his girlfriend and her family are guests in this house (no rental agreement/lease was made). Since they said they would pay rent (and haven't), my parents have asked them to be out of the house by June 1st. My question is this: If by June 1st they are not moved out, can I legally remove their belongings, and change the locks?

His girlfriend says that we have to legally 'Evict' her, and that we have to give her 30 days notice. Since then, she's tried to break apart my family and has been trying to stay. She wrote my mother a couple of angry emails, and my mother said in the email that they were to be out by the 1st. My parents own the house. I tried looking up the laws, but all of them involve a lease. Can someone help me?

No, you can not change the locks and remove their belongings.

Did you give them written notice to move ? If so and they did not move, you and file in housing court for a formal eviction.

yes if you just lock her out, they will sue you and you will pay them 1000's of dollars for a illegal eviction and the value of any and all property that is lost and damaged.

And for court most likely you will need written proof you are acting on behalf of your parents.