Legal Question in Wills and Trusts in California

You don't have any say about what your parents put in their wills, nor do you have the right to know who they are planning to leave their estate to, while they are alive. After they die, if you are an heir, you may disclaim your interest (if you still don't want your inheritance after our children die, consult an attorney- there various requirements for a qualified disclaimer, stemming from federal tax law.) In that case, your share would probably go to your children, or if none, to your siblings. If you mean you don't want to be their executor, you can also decline that when the time comes, but there is nothing you can do about it now, except to let you parents know you would be unwilling to serve.

Even if you do locate your parents' attorney s/he cannot tell you anything about your parents' plan, while they are alive.

correction: line 4 "still don't want your inheritance after your parents die...."

If you want to be disinherited, just keep annoying them. Distance yourself as much as possible and cause all kinds of family problems. Try to be the biggest troublemaker you can. Sooner or later, they will have the attorney cut you out of the will, and anything else.