How to clean ring in slow cooker?

Have you tried a vinegar soak?

I scrub mine with a mesh pot scrubber. Once clean, either spray with a cooking spray (think PAM) or rub lightly with cooking oil using a paper towel to apply.

I lightly grease the crock portion. Then, after removing the chicken, I fill the crock with warm soapy water and let it soak overnight. Usually comes completely clean.

Soak the ceramic part overnight with water and baking soda, that works miracles.

Put baking soda in water and heat it up. Let sit for a while and it should come off with a scrubber.

Have you tried non stick spray first also Reynolds oven bags work in the cooker to cook in