How did Hitler die?

Adolf Hitler died by committing suicide on April 30 1945 in his underground bunker (Fuhrerbunker) in Berlin. He shot himself with a pistol while his mistress, Eva Braun, died by ingesting cyanide, a deadly poison.
To put Hitler's suicide into context, a Nazi victory in the war was no longer possible. Stalin's Red Army had already captured Berlin, leaving the Nazis in a hopeless situation. Moreover, the Allied forces were positioned to the west of Berlin, ready and waiting to provide support, if needed. 
With the Red Army poised to take over the German chancellery (which stood above Hitler's bunker), Hitler had few options. He could risk escaping the city to go to the Berchtesgarden, his home in the Bavarian Alps, could surrender to the Red Army or commit suicide. Hitler chose the latter. 
See the reference link provided for more information. 
https://www.history.com/this-day-in-history/adolf-hitler-commits-suicide-in-his-underground-bunker