How to remove a watermeter lock?
Pay the bill.
The meter is not yours, neither is the lock. Removing the lock is illegal. You will be charged with theft if you do.
When you pay the bill the water company will remove the lock. If you do it yourself you will be put on a list of problem customers and may be required to post a large advance payment - sometimes thousands of dollars - to continue service.
Somebody is being naughty.