Legal Question in Real Estate Law in California

Nope. When property is co-owned, each owner has the full rights as if they were a sole owner. So conflicts such as who to allow on the premises, which tenant to rent to, whether to sell and when, all have to be worked out, or the property must be sold in a partition action if either party decides to request it.

I agree; one co-owner cannot dictate or control use of the property versus the other co-owner. You'd have to resort to sale by partition or, possibly, there are other reasons (unlikely, I admit) that might dictate that he be moved out such as insanity or criminal conviction.