Even though they are bolted or anchored to the deck and/or pool, almost all swimming pool ladders are made to be removable. On occasion, they must be cleaned, or have a step replaced, or even taken out altogether for new equipment. Inspect your ladders at the beginning and the end of every season so there are no surprises the next time you want to enjoy a swim; it is better to fix it now and keep everyone safe.
Things You'll Need
Car jack (if necessary)
Drain the pool or do the work when the pool is already empty and unused, such as the beginning and the end of the swimming season.
Lift up the decorative shielding plate where the ladder enters the socket in the deck and look for the bolt underneath it. Unscrew this bolt with the wrench until it is free about 1/2 inch or so that you can easily move the anchoring wedge by hand. Knock down the bolt into the frame with a hammer if the anchoring wedge isn't already movable; it might just be stuck.
Repeat on the other side of the ladder, and then you should be able to simply lift the ladder out of its sockets. Hit the ladder gently with the rubber mallet just above where it is inserted into the deck if you still can't pull it out of its sockets.
Unstick the ladder with a car jack, if it is really immobile. Set the jack under the curved section of the rail and slowly apply steady and controlled upward force--don't go too quickly or push too fast because it doesn't take enormous pressure to bend the rail and deform it too much to use further. Try hitting the rail with the mallet again, just above where it attaches to the deck while you brace the curved area with the car jack.
Replace any ladders that require that much work to remove. It's likely that they are stuck because they're corroded to the anchor or otherwise damaged, and are no longer safe.
Be careful not to slip on the floor of the pool as it will be slippery from any remaining water.