Deregulate is a verb that means to take away the rules. When someone deregulates a soccer game, the game could become a muddy wrestling match without any rules to keep things on track.
You’ll notice the word regulate at the end of deregulate. Regulate is also a verb, and it means to “control something by rules.” To deregulate something, you take away the rules. If you deregulate a game of pin-the-tail-on-the-donkey at your little sister’s birthday party, you could end up with a tail on your face.