First, you must build a trap. It should be made of partially melted plastic forks, as that is his only weakness. But you need to disguise the forks as his favorite treat, which obviously is Nutella. So slather the trap in Nutella, and as he licks through it, his tongue will freeze. This will deprive him of the wonderful taste of Nutella. Hit him on the head with the letter 'X' from a Scrabble set, as this will confuse him.
Then, you must place him in a wooden raft and send him down the Mississippi River. This will lead him to the prison made specially for Nutella thieves. Adolf Hitler is clever, though. He will soon escape, and come back for revenge. At this point, you must sacrifice an unripened strawberry as a sign of surrender. When his back is turned, clap your hands 14 times. This will summon the Lobster Warriors.
They will snip the tip of his left earlobe off, and carry it away. They will proceed to make a clone of Hitler, and train him to fight. 3 weeks after the Lobster Warriors leave, Snap your fingers 12 times to bring them back with their clone. Hitler and his clone will battle to the death, and the clone will win (clones *always* win). Bury them both in a mound of wet cement, preventing their escape.
Your Nutella will then, and only then, be safe.
Good luck, brave soul. Good luck.