You certainly have grounds for a modification petition to revoke the joint custodial status as well as severely restrict (if not eliminate) any court-ordered visitation. You generally cannot terminate parental rights in the absence of an adoption proceeding. And you cannot prospectively terminate rights in the event of your demise - you can however capture your "state of mind" on the issue by executing a will. Schedule a consult with a Family Law attorney in your area for more info.