Then add lemon juice or vinegar to your stew ½ tsp. at a time. Taste the stew after you have stirred in each addition. Stop when you can taste the sour ingredient. Sour flavors balance out sweet flavors to an extent that helps make the flavor less overwhelming.
Then, pour salt into your dish in 1/8 tsp. doses until the sweetness is no longer as noticeable or until you start to taste the salt. Be careful with how much salt you add because most stews have a tendency to be salty.

More is NOT better! Measure the vinegar and salt VERY carefully.

Or, make a second batch with considerable lower/ no sugar, and combine them. You will now have twice as much, but flavor balanced.

Or, some people use a cup of VERY strong roasted coffee, added a little at a time.