How do I remove burnt food in bottom of pan?

I forgot to check on my greens beans in my stove top pressure cooker and now can't seem to remove all of the black residue. I've tried everything .I need to use this soon !!!

Vinegar and baking soda. Make a Paste. Apply and let it sit for 5 to 10 minutes. Scrub it with a Steel Wool Pad. Reapply the Paste until you get it all off.

oven cleaner

Denture cleaner is very good to use. Break up about 2-4 in very hot water. Let sit for about 10 minutes. Repeat if necessary. Pick up a box at the dollar store.

Just put water in your pot and boil it , then scrub it with a steel wool soap pad! Sometimes I boil dishwashing soap too the water. Hope this helps.

Thank you all. I tried a few suggestion but I may retry :)

Cover bottom of pan with hot water and then add salt to pan and leave overnight ,,, burnt bits should just wash of xxx