Before walking into the Forbidden Forest, Harry uses the Resurrection Stone to ask Dumbledore if he has any ideas for how Neville can destroy Nagini. However, Dumbledore gives a very unexpected response.

“Harry my boy, I’m sorry I didn’t tell you this before, but you’ve actually had the power to destroy all the Horcruxes all this time.”

”I have? Why didn’t you tell me that?”

”Because you wouldn’t have believed me, my boy, you had to learn it for yourself. I needed to put you through the struggles of the Horcrux Hunt and then made you think you had to die to help you mature and learn more and be able to truly understand your destiny and obligation as the subject of Trelawney’s prophecy. It also helped you learn the lesson to be grateful for what you have and understand that the life with the Dursleys I put you with wasn’t so bad compared to what you had to go through during that journey. But if you’re ready now, all you have to do is tap your scar three times and think to yourself “There’s no evil like Horcruxes”, and Nagini, Voldemort, and the Horcrux in your scar will all be destroyed.“