its hard to get a freewheel of a hub that isnt laced into a rim
if it isnt, lace it up, roughly. or you will struggle and maul the hub
if it is laced into a wheel, get a tyre and tube on it, so you got some grip.
if the freewheel has been on for a long time, bolting the freewheel remover on helps.
if there is not enough axle to get the wheel nut on aswell as the tool, can you spin a bit through from the other side?
if the freewheel is expendable, get it in a vice, crush it a bit and just turn the wheel off it. the freewheel will be fubar afterwards
oh and while on the subject of freewheels, never ever ever ever spray wd40 in it. it will kill it in seconds. try it on a scrap one