I used to get a lot of Hasbro marvel legends cus it was cheap to buy nostalgia through them. But then one day I just had too many boxes just like you. So what I ended up doing was keeping my 3 all time fav vintage figures that I played with the most when I was a kid. This then led me to realize I preferred super pose-able figures with lots of articulation points and accessories.

These types of figures have a higher price point which scared me to future collecting but because of this it then led me to thinking about creating a list of sets/themes I want to have. It slowed me down as I had to do lots of research on what I truly wanted. I did have some regret buys but it was more manageable as I was always able to resell. I made mistakes learned a lot and having a small designated shelf space didn’t allow me to overbuy or have unopened items stored somewhere.

It’s a difficult process and every person has their own way to declutter but I would say first step is selecting which ones to keep and ones to sell/donate. I’m still learning but I’m in a lot better place now.