Need advices on eviction

[Timon Tran]

Hi. I am a landlord of a single-family unit. I had a verbal lease agreement with the tenants. Now, they cut off communication with me and refuse to pay the rent despite me trying to contact them and knocking on the door. I feel they are doing something shady inside my property, and I passed by the property several times and saw no vehicles or people. Last morning, I saw a strange car or person going in and out of the property. I sent them a "notice to pay rent or quit" through certified mail. At this point, I do not think they will sign to receive the mail. I believe I got scammed. Should I keep proceeding with the eviction? Can I go back into my property and change all the locks now?