You should definitely be able to disassemble and cut the freewheel off.
There should be a ring at the front with some notches around it, undoing this should allow you to remove the cogs and the eventually the bearings, pawls etc leaving just the inner part of the freewheel. Cut a slot through that - very carefully - with a dremel etc and it should free off the pressure. You'll probably nick the freewheel threads on the hub but if you just cut one fine straight line it shouldn't be too much of an issue.
You should definitely be able to disassemble and cut the freewheel off.
There should be a ring at the front with some notches around it, undoing this should allow you to remove the cogs and the eventually the bearings, pawls etc leaving just the inner part of the freewheel. Cut a slot through that - very carefully - with a dremel etc and it should free off the pressure. You'll probably nick the freewheel threads on the hub but if you just cut one fine straight line it shouldn't be too much of an issue.