Bob and tricia are partners. they orally agree that bob will have the sole right to manage the affairs of the partnership. is this valid?

Yes. The oral agreement is valid as long as one of the partners agree to relinquish his or her managerial powers.

For any contract, written or oral, to be valid there must be an offer and an acceptance. If offer is given but unaccepted, contract is invalid and unenforceable.