Try Bio Cleaner paste.
Here's a post that might help you - https://homesteady.com/how-5997559-do-spots-glass-table-tops-.html
What is the spot from? Scratched --buy glass polishing kit; water marks? put white vinegar on it let it sit then wipe with scrubber sponge
if it is from a substance, try to scratch it off with a very sharp Xacto blade. If it is from being scratched, try buffing with a very light emery board.
Try Bar keepers friend or toothpaste or WD-40. Best wishes.
I like to use a Magic Eraser
Have you tried vinegar and a microfiber cloth?
Hi! I might try Soft Scrub --- GENTLY!
If its something like glue or wax, I would use single edge razor blade at a 45 degree angle to shave it off.