Looking closely at the freehweel it appears to have internal threads, and therefore is simply screwed on. But I don't see removal notches, so I suspect that they expect you to work like a third world mechanic, and set a small punch into one of the two notches and tap it off. The cover loosens to the right, so tapping counter clockwise should remove the freewheel as a unit. SS freewheels aren't as tight as typical multispeed freewheels so it may come off fairly easily.

Otherwise find an adjustable pin spanner (or a bike co-op that has one), set it into the two pins, make a bridge with a piece of scrap with a hole in it, and use the axle nut to keep the pin spanner jammed in so it can't jump as you turn it, and turn the freewheel off a few degrees, then remove the nut, and take it off the rest of the way.