This is the script that gets called by an editor utility widget button. I modified it a little from class- instead of searching through all textures, it only gets the assets the user has selected- just like the "get selected assets" blueprint node.
I have a list of suffixes written out for textures that should not have sRGB turned on.
For each asset, it checks to see if it's a texture first, then if it has the suffix, and last if sRGB is already off.
On textures that qualify, it'll disable sRGB and save the asset.