Do you have to withdraw your rights and obligations from a contract? Learn more about the basics of an assignment and acquisition agreement. By editing the contract, you can modify, delete or supplement an existing contract. Learn how to change a contract and what to avoid. If your company has a contract with another company or person, both parties are bound by the contractual conditions and are legally obliged to comply with them. However, situations may change and circumstances may require an update to your contract. To do this, you must create a contract change. As with a supplement, you can also use a change as a landlord or tenant. This may come into play if you need to change the termination date of your rental agreement or other terms of your contract. It can also be called editing the original document.