Outer nut is a reverse thread. IOW, clockwise loosens it, ccw tightens it. Try a pair of sharp tweezers but I suggest winding the self timer all the way before taking apart. If the self timer is allowed to unwind all the way, you'll have trouble getting it back together. John, www.zuiko.com
I use a small pair of pliers with the tips ground down. Dremel type grinders are good for that. bear in mind that the shape of the ends doesn't want to be tapering points (which will tend to slip out of the holes) but parallel-sided that are also parallel to each other at the opening gap of the pliers that will be needed (as you would expect to see on a pair of circlip pliers). It's well worth spending the time to make something fit well before trying to undo a camera part that may have been there since it was assembled many years before.
Is there scope for a dedicated "Camera Repair and Maintenance" section on APUG?
Rewind knob unscrews counterclockwise. Do NOT remove small screw from center of knob. It's only purpose is to level the rewind handle when it is lying flat. Screw usually breaks off 'cus it's glued in. Grip both blades of rewind fork with pliers and turn knob counterclockwise. Do NOT put object between forks when unscrewing, this could bend or break a rewind fork off. ASA knob does not come apart. John, www.zuiko.com