The hard way is to use elbow grease along with something like Comet, Ajax or some other similar ABRASIVE cleanser.
For my homemakers that are young and or just don't know; elbow grease is using your hands and and other muscles to complete the task.
Those two cleansers I mentioned contain bleach as well.
Use something like a Chore Boy Golden Fleece scrubbing cloth and wet it just enough to turn the cleanser into a paste. That way the cleansing agents don't become diluted and weakened.
You'll probably have to scrub the dish a few times to completely be rid of the stain.
Now the easy but requiring a whole lot of patience way.
Use a soap and ammonia solution; HEAVY ON THE ammonia and let it soak for however long it takes to break up the color.
Usually, I go the abrasive cleanser and elbow grease route.
It doesn't take as much time or elbow grease as it sounds.
And in the future, might I suggest that you line you plastic containers with plastic wrap BEFORE putting in the chili or spaghetti with and or the sauce.
You'll still be able to reheat in the microwave in that container and just throw away the plastic wrap when the food is gone.