Buying a home where a tenant refuses to leave.

[O'Neil Mbakwe]

So I recently got a home under contract in Waco, TX. Currently, the owner of the home rents it out to a tenant though there isn't a lease agreement. The seller informed the tenant that she was selling the home, but the tenant did not take it lightly and has gone incognito. She's not at the house, nor is she answering phone calls, and she has the only key to the house. I'm looking to close on the property pretty soon, and I don't want to go through an eviction process. If I close on the property after giving a 30 day notice, what can I do to ensure that the tenant leaves.