That won't work on a motor wheel! He has a 14mm axle.you only need a cheapo £2 freewheel removal tool and an adjustable spanner for the Shimano TZ21.
You can pay more for a proper Park Tool job but there is really no need.
This one costs 99p:
http://www.ebay.co.uk/itm/Bicycle-Bike-Cassette-Flywheel-Freewheel-Lockring-Remover-Removal-Repair-Tool-HS/371719893927