Obviously you should not suddenly ditch the belt if you have been depending on it for 10 years; that is just asking for a bad injury. Start doing your fist light warm up sets without a belt, then just gradually start doing more and more of your sets without the belt. It won’t be long before you will wonder why you ever bothered to use one.
I should clarify a little. With squats I do 3 warm up sets then I use the belt for 3 working sets. With deadlifts I do 3 warmup sets. then one set without the belt then 2 more sets with the belt and like 50lbs more. I rarely go over 6 reps in any working set.
Personally the heaviest squat I've ever seen in person (495lbs - I don't get out enough) was done by a guy without a belt.