In the process of cooking, foods are often placed into plastic containers and put back in a cool oven. In the case that someone turns the oven on to warm up foods only to realise later they are in plastic containers, the plastic can melt onto the oven itself. The plastic hardens quickly once cool air gets in, and removing melted plastic from the oven requires heating the plastic to a softened state and scraping it out of the oven.
Pull the cooking racks out of the oven. If the racks have melted plastic, soak them in a sink full of hot water with 2-tablespoons of dishwashing liquid.
Turn the oven on to 121 degrees C and allow it to warm the melted plastic in the bottom. This temperature is warm enough to soften the plastic and still allow you to work inside the oven to remove it.
Grab an old soup can or coffee can with the top removed. Scrape the softened plastic with a hard plastic spatula or putty knife. Turn off the oven once the plastic has softened.
Scrape the plastic you remove into the can, avoiding touching the plastic with your hands. Continue scraping the plastic out of the oven with the plastic spatula or putty knife.
Put the oven in self-clean mode and allow the oven to burn off the remaining residue if you have a self cleaning oven. Apply some oven cleaner to the residue and allow it to sit for 30-minutes if you do not have a self cleaning oven. Wipe off the oven cleaner according to the instructions on the can.
Scrub the wire cooking racks with steel wool to remove the plastic from the racks. Rinse thoroughly with clean water and allow the racks to dry.