M.K.
Hi D.. Have you tried using bleach? Bleach is used in restaurants/food service venues as a cleaning and sterilizing agent and can can safely be rinsed.
In the future, you can try our trick: we spray the tray with Pam (or any oil spray) before serving the food. After the meal, use cold water to wash the tray with soap. The red sauce should slide off easily and should not stain. Once there's no trace of the red sauce, you can wash again in hot water.
Good luck!! :)