Place hambone, onion and bay leaf into a 6-qt Instant Pot®. Add enough water to almost cover the bone without passing the max line of the insert, about 7 cups.
Select manual setting; adjust pressure to high, and set time for 30 minutes. When finished cooking, quick-release pressure according to manufacturer’s directions; remove and discard hambone and bay leaf.
Add ham, carrots, potato, beans, corn, garlic and thyme. Select manual setting; adjust pressure to high, and set time for 5 minutes. When finished cooking, quick-release pressure according to manufacturer’s directions. Stir in parsley; season with salt and pepper, to taste.