After you cooked a chicken it was out on the kitchen table for about 4 hours Can you reheat it to make it safe to eat?

Potentially hazardous foods should not be unrefrigerated for more than 2 hours. After that, it should either be thoroughly reheated or placed in the refrigerator.

Four hours is pushing the window at room temperature. If Staphylococcus aureus was growing on the food and formed toxins, heating would not make it safe.

Without microbiological and chemical testing, no one can tell you it is safe. You will ultimately have to make the decision of whether to use it or not.