AITA for throwing away my friend’s old belongings without asking?

I (25M) recently helped a friend clean out a storage room that had been unused for years. While cleaning, I found several old boxes that looked like they had been forgotten and were taking up a lot of space.

I asked my friend about some of the bigger items, and he said he wasn’t sure what he wanted to do with them. I assumed they weren’t important because they had been sitting there untouched for a long time. I ended up throwing away a few things, including some old papers, clothes, and random items from the boxes.

A few days later, my friend asked where those things were. When I told him I threw them away, he got really upset and said some of the items had sentimental value and that I should have waited for his permission.

I apologized and told him I honestly thought they were just things he no longer needed, but he said it wasn’t my decision to make.

I feel bad that I upset him, but I also feel like the items looked abandoned and were taking up space.

AITA for throwing them away?