If you have previously recommended this thread, you should see a tick / check mark on the recommend button. Click the tick to undo the recommendation (the tick may appear to change to a cross as you do this.) If you added a comment with your recommendation, you will need to delete that from your facebook wall separately.
North Herts has facilities at Hitchin (pool) and Letchworth (leisure centre and pool). I'm sure there must be something nearer Welwyn though. Hitchin pool has vile changing rooms and showers. Letchworth has ok showers but vile loos. I avoid both like the plague! Slightly further afield, there is a fabulous looking pool and leisure centre being built in Stopsley (edge of Luton, going towards Hitchin), due to open this summer.