Deflating a football is necessary if you accidentally added too much air inside of the ball, if you are placing the ball into storage, or putting it inside a suitcase before travelling. Placing a needle that is used for adding air into the football can also cause air to rush out of the opening found in the centre of the ball, but if you're without a needle, you can use some basic science to deflate the ball.
Clean the outside of the football with a damp towel. Remove all visible dirt and debris from the surface.
Move things around inside the refrigerator, as needed, to make room for the football on the top shelf.
Place a cloth or dishtowel at the very back of the top shelf of the refrigerator.
Place the football on the cloth inside the refrigerator. According to the Natural Horse Talk web site, which markets a ball for horses and provides instructions, air expands when heated and condenses due to the cold, so you can use temperature to regulate the amount of air inside a ball. Inside the refrigerator, where the air is cold, a football will deflate.
Check the football every couple of hours until it has deflated as much as you wish, or leave it inside the refrigerator until it fully deflates.
Avoid placing the football inside a freezer, as the extreme change in temperature may damage the football.