Advance springs

With the clip out, the slot plate slide up and off the shaft.
Wait, the clip in your photo? That's a royal pain. I don't have great tip to make it easier. Needle nose pliers and sometimes a very small screwdriver to slip between the shaft and the clip.

If you want to adjust the timing from more initial, lets see what the number is on the plate, and tell us a bit more about what you're trying to do. With early emissions, Chrysler retarded the initial timing and made up for it off idle in the advance. Depending on what you're trying to do, and what's been done to the engine, often I think the best is to just shorten the slot on the inside (weld and file). Sometimes, an easier work around is to use manifold vacuum source for the vacuum advance.

There's a couple of example of welding up the inside of the advance slots. Lets see if I have enough internet here to find at least one.