ohoh a Carter Clover hub..
that thing is close to a unicorn these days..
it's not available any longer,
and having an odd bolt hole circle it's the only known way to mount the original wheels.
pb blaster & patience is the way to go, the aluminium is too soft for mallet persuasion,
once cracked you need new hubs and wheels
if you can hammer the key out though you should...
it gives the penetrating oil a nice head start
the other end of the throttle cable will likely fit through the hole

just release it fromt he throttle plate and you can pull it through..
but if you're going to replace it anyways.. why not cut it?
'sid