Scientists accidentally kill world's oldest animal at age 507. The oldest animal ever known lived from 1499 until the day researchers cracked its shell open, killing it in the process.
For example, there is a federal law (and similar laws in every state) allowing consumers to cancel contracts made with a door-to-door salesperson within three days of signing. You might use that law after hastily agreeing to have someone repave your driveway, deliver lawn fertilizer, or put a new roof on your house.
You need to look for the cancellation clause in the contract. The clause will have instructions for rescinding the contract. It will also tell you the time frame that you can do this within. If you are still within the time frame, you need to follow the instructions in the contract to cancel it.