Do I need eviction notice?

[Hiren Patani]

Rental property is in Houston, TX. Lease is ending at the end of this month (i.e July 31st). Tenant started acting weird from last month, first they said they will move out and then they are saying 45 days is not enough to move out, have lot of stuff, etc. They are not even allowing me to put a lockbox on the door to show to any potential tenant, saying it is invasion of privacy. Also, has not paid this month rent. My question - If they don't move out by end of July 31st, can i call police on August 1st and kick them out or do I need to go to court and order eviction? If we go to court for eviction process do I need to wait 30 days (after 31st July) before they have to vacate the property. How can this be resolve in friendly way? What's are my rights as an landlord and what's the eviction process in houston, TX? any help will be greatly appreciated.