For the clear a specific item script, you can make it where it takes all of them items instead of taking one. In your example, if they had more than one sledgehammer, one sledgehammer would be taken away and they would still have another.
Here's a script I would use:
HasInventory [player] [sledgehammer] [true]
Inventory [player] [clear] [sledgehammer]
Notify [No sledgehammers allowed!] [local]
Great videos though. Keem 'em going