Using less colours in your sprite/animations to reduce their overall size. See if there are any animation frames you can cut out completely. Could backgrounds be cut into smaller pieces? Make sure sprites are cropped. These things could help you.
The only way I know of is to delete stuff in your game. I don't think you want to do that. Delete code in the event sheet that doesn't do anything. Delete the worst levels? If you have a lot of the same code in your event sheets have a main sheet that stores all the same code. I have to look at the file