I found my tenant made some arrangement in the garage and someone is living and cooking inside?
2 attorney answers
The use of the garage as living space probably violates multiple provisions of your lease, including restrictions on nuisances and subleasing.
Immediately seek help from a local landlord-tenant attorney, who can draft and serve an appropriate notice to the tenants (see e.g. Code of Civil Procedure Sections 1161 and 1162).
Do not accept/cash rent until you consult the landlord-tenant attorney, because doing so (after learning of the violations) often waives your right to evict for those violations.
You should act to protect yourself. Give the tenant and all occupants a three day notice to comply or quit. They need to move out of the garage.