Hi Marcia, you could try this method. https://www.hometalk.com/29728727/easiest-way-to-clean-a-microwave
Here is a great way to do just that! I know it works for me.
Put a large bowl of water with lemon juice in it in the microwave and run it until the water boils (uncovered). Let sit a few minutes to get steamy and wipe the microwave down,
I fill a glass measuring cup about halfway with water, run the microwave until the water boils, let it sit and steam (don’t open the door), then after several minutes just wipe it down.
Put a bowl of water in the microwave, turn it on high until the water boils. Let it sit a few minutes then just wipe it clean with paper towels.
1 cup vinegar
1 cup water
Please in a microwave safe bowl. Spoon is to prevent overheating. Turn on for 5 minutes. Remove with mitt. Wipe clean.