Anyone know how to get this lefty fork off

Remove the stem, then loosen the bold on the side of the purple bit. It will pull off too, allowing the fork to drop out the bottom.

You use a bottom bracket tool to loosen the threaded steerer that the 2 crowns are pinching.

I would do it in this order:

With the stem still on, loosen the pinch bolts on the fork crowns. Then use the bb tool to loosen the steerer insert from the bottom. You can use the bars for leverage. Once that is loose you can likely pull up and the steerer insert will come out while still attached to the stem.

If it is one where there is not a keyed face for a bb tool, this thread has some info you can use.

https://singletrackworld.com/forum/bike-forum/old-lefty-fork-removal/