Swing arm finish

Vapor blast and fine scotchbrite.

Weren’t they clear powder coated?

Clear anodized I believe

Spray oven cleaner removes anno. You can do a lye bath too, tub of water and a cup or two of drain cleaner that contains lye.

The clear anodize from the factory has broken down. I've had good results removing it by soaking in industrial "purple" degreaser, as Kidkawie mentioned any acid will strip it and there are probably some other good methods on the internet. It will strip it off and leave the alu a black mess that you'll have to scrub clean with a stiff brush and scotch pads to remove that and you will have a raw alu swingarm when finished that looks pretty good but won't have any protection on it, as long as you keep it wiped down with WD-40 it will look good for a long time. I'd recommend a tub large enough to completely submerge it so it's even and doesn't etch a line into it, (ask me how I know this).
An anodizing shop can strip and re-anodize it for probably less than you think. I just had a set of rims clear anodized and it was about 50.00 bucks.

If your not into having it factory finish... look into cerakoting it really happy with how my cr 250 came out , i think its glacier silver

Warm water and lye and then a clear coat