Re: Wiper grommets the same?
Loosen the nut until almost off. Spray some penetrating oil (PB Blaster, etc...) down around the splines. I had to use a battery terminal puller to get both of them off. I found them to be corroded (different metals) and caused them to be locked on and they were harder to get off than I expected. Both sides had caps on them so they didn't help at all.
Keep the nut on the shaft so you don't mushroom the threads on the shaft when using the terminal puller.
James