Legal Question in Real Estate Law in California

Yes. Each joint tenant has the right to sever the joint tenancy. You can expect the recorder, at least in the LA area, to provide a copy of the deed to the owners of record.

Yes you can. It is called severing the tenancy and is done all the time.

The only exception to the previous answers would be if there was some Joint Tenancy Agreement in place that prohibited it. Even then the severance would probably be effective, but it would result in breach of contract damages.

I agree with the previous answers. I write separately to point out that severance of a joint tenancy cannot be done by a will. It is usually done with a deed. There may be other legal requirements as well, so I suggest you at least consult with an attorney in person rather than rely on any of our assumptions.