15 random minutes would not be enough to change much, including suicide. His henchmen would have easily carried the Machine onward with another frontman. First, I can't speak German. Second, 15 minutes would not be long enough to enact any significant change other than change of leadership. If I could select the 15 minutes, I would become Hitler right before a meeting of his biggest henchmen, like Himmler, Goering, etc. I would draw my firearm (hopefully more than one), shoot as many as I can with two bullets left, and shoot myself (two bullets in case of a misfire).

Not attack Russia in Operation Barbarossa or declare war on the US in December 11, 1941. Everything was going according to Hitler's plan when Nazi Germany quickly took over Europe, while England was close to defeat. But Hitler became delusional, thinking his forces were unstoppable. Once the US got involved, liberated Italy to divide the Axis powers and landed on Normandy along with Canada, England gains momentum and Russia attacks from the East - Germany was sandwiched: https://youtu.be/R5i9k7s9X_A?si=T1Ua3vjr-5b-fjrB

Hard pass. What-ifs are fun, but the path of human history is chaotic. Change one parameter way back in time and the present would be totally unpredictable. For example- what if Hitler never existed? Well, are we forgetting that Mussolini was already on the warpath prior to his rise? There would have just been some other extremist dink who got everyone's attention. Heck, maybe that replacement extremist would have somehow been worse. What if you delted Mussolini? Well, he got his ideas from Enrico Corradini, who would have merely chosen a different protege, again, maybe someone worse... so what if you deleted Enrico Corradini instead? Well, he was merely a follower of Gabriele D'Annunzio, and so it goes on and on until you get into historical obscurity. We like to think these historical events happen in a vacuum. Maybe stop the assassination of Franz Ferdinand in order to prevent WWI, which really eliminates the root cause of WWII - but Ferdinand had already staved off multiple assassination attempts! If he hadn't been shot, he likely would have been poisoned or blown up or had a piano dropped on him moments later! And it really wasn't the assassination alone that led to war, but the uprise of nationalism and the general unhappiness of people midway through imperialism that led to it. How would you stop imperialism?! Even if Franz Ferdinand had been locked in a steel vault for the 1910's, something else would have touched off the powder keg , anyway. We never understand the implications of these what-ifs. What if Stalin had stayed with the Axis powers? Well, he wouldn't have. He never planned to do so from the start, and even if he had been replaced with a robot to keep the USSR with the axis, we cannot predict how it would have worked out for anybody.