A good technique that scientists have found to help obese children with sweets is to imagine the food you're craving. You are to imagine every single detail- the taste, color, texture, smell, how it feels in your mouth (giggity) etc. Usually, afterwards, you find yourself not wanting to eat it anymore because you used up the dopamine it took to imagine eating it it rather than actually perform the action.
Keep a travel toothbrush and a small tube of MINTY toothpaste with you at all times. When the craving starts up, give your teeth a quick brush (even in the nearest public restroom). The aftertaste of the toothpaste will spoil the taste of the chocolate (or anything else you eat soon after) and give you time to distract yourself. AND your breath will be "minty fresh."
This may sound crazy but when I was in Graduate School I was dating a Chinese student and took to Chinese foods. The one thing I noticed is that they did not have sweets in their diets. If you go to Chinatown in New York City you will find that the restaurants on the ground level floors are for Americans. To really eat Chinese foods one must go to the basement restaurants which serve authentic unsweetened Chines meals. Anyway I started to snack on a sweet onion in the evenings which really deterred my taste for chocolate. After a while I began to enjoy snacking on an onion and as a result started to eat clean without having cravings for chocolate. Good luck on your endeavor! Once you lose your weight you will be surprised how your whole life outlook changes. Go for it!!!
Since you are craving sugar, you may need to eat a balanced meal with everything in it (same amounts of meat, carbs & veggies on a plate), to balance your blood sugar. Otherwise, you will most likely continue to crave the sugar. Good luck