This was on my '72 Demon's keyless latch. I don't know if it's the same as the keyed latch.
1.-- Remove the two screws holding the latch in place for better access.
2.-- Push the catch so it is held in the closed position.
3.-- Find the small slot in the bottom of assembly toward the door.
4.-- With a wire ( I was able to use a small pick) depress and hold the small spring loaded
tab. You can then insert a small wire into the hole in the front of the latch which will retain the tab
5.-- The knob should now pull off the front of the door ( holding light pressure to the catch
toward the closed position may help).
6.-- To ease reassembly a small wire may be inserted in the hole in knob while holding the
tab depressed. This will keep the tab in place.
7.-- Slide the two pieces together in proper alignment untill the tab is in position and remove
8-- Replace the two screws holding latch assembly and your done.