Originally Posted by
Iride01
Pic is pretty tiny. Looks like an old one-piece Ashtabula crank. There should be a big nut on that side shown where the crank arm bends to go to the other side.
N.B. the nut, and the cone it secures, will be
left-hand thread, so clockwise to loosen.
If that nut can be loosened, then undo it all the way and remove it and all the stuff under it on that side. Before you do that get the chain guard off the other side. Because that's the side the entire crankset removes from after you get the nut and other stuff off the side we are currently looking at.
And the pedals will need to be removed before you can pull the crank arms out of the frame. I suspect lots of penetrating oil on all the threaded pieces will be needed, and perhaps judicious application of heat.