A delegator can be discharged from his/her obligation to perform his/her duty to the original promisee by a contract of novation.

Novation

A mutual agreement, between all parties concerned, for the discharge of a valid existing obligation by the substitution of a new valid obligation on the part of the debtor or another, or a like agreement for the discharge of a debtor to his creditor by the substitution of a new creditor.

Delegator

A person or entity that assigns tasks or duties to another party (the delegatee) while maintaining ultimate responsibility.

Obligation

A duty or commitment requiring an individual or entity to act in a certain way, often legally binding.