Go to your local to the courthouse, civil division. Ask them for a packet for an eviction. You will complete this, have a 3 day quit or notice served on your tenants. You will have to have a process server or the sheirffs department civil division serve them. You cannot not serve them because you are an involved party.
Once served they have 3 days to respond. If they respond, then they have 2 weeks to court for a hearing. If they don't respond, then you get an unlawful detainer, have that served on them. Then now in California, they have 60 days to leave. If they do not, then you get the sheirff to remove them. Most of the time, they just leave, because, they don't like the hassle.
If you suffer any money lost $5000 or under, go to small claims court, sue them. Its cheap and easy. Once you get the judgment, go to
Liberty Judgment Recovery.
This company is awesome at collecting, they can also assist in collecting child support judgments.