find someone with a big vice bolted to a bench,
Get a proper freewheel tool
put it on the freewheel
and bolt it on with bolts and washer, this stops it sliipping and rounding your freewheel
then put the tool in a vice
get a long bar about 1Metre long
slide it over the crank arm
and turn
freewheels come off so easy this way:)