This post could have been written about me at age ten! The thing my mom did that worked well was, she’d pick up a bunch of what she thought was junk and put it all in a box in my room. Over the next 2-3 weeks, I could retrieve things from the box if I found myself wanting or needing them. After that, the whole box and its remaining contents went away. The “out of sight, out of mind” effect meant that within a few days I had forgotten about most of the box’s contents except a few genuinely useful or sentimental objects.
The other thing I would say, though, is ~ what’s your goal here? If it’s simply getting rid of clutter, you might find that goal is nearly impossible with a kid with ADHD, and it might be more peaceful to just let her keep that soarkly duct tape. If it’s some deeper goal about how your kid relates to her stuff, I can tell you from experience that there is some degree of growing out of it, but therapy might also be important.