Try putting his diaper on backwards.
Try putting some duct tape on his diaper or some packing tape. Putting tape all around his diaper will sometimes prevent your child from removing their diaper.
If that doesn't work you should try the little keeper sleeper. This child sleeper is designed so it's hard or impossible for your child to remove the sleeper on their own.
If they can't get at their diaper then they can't remove their diaper.
Don't worry this will all pass and although you might not think of it now. You'll miss this time.
He might also be ready to potty train, you can always try and get him to use the potty. It's worth a try and if he succeeds in potty training then you won't have to change anymore diapers or deal with diaper removal.