If the key you are removing is the spacebar (like you see pictured here), you should find a single spring placed on one of two circular spots located one the right and left side underneath the key.

Remove the spring and place it to the side so it doesn't get lost.

It does not matter which of the two circular spots the spring is on.

There is only one spring per spacebar. If the spring is missing, don't worry — the spacebar will work fine without it — but it will work better when the spring is attached.