Decluttering useful things is hard for me. Harder than decluttering decorative things, or sentimental things. If it's useful, or something I should use, then why am I not using it?
Case in point: I have a face scrub that is half used up. It's very nice face scrub. I just usually wash my face with soap in the shower -- I don't think to use the scrub. It needs to be kept out of the shower because it is a powder, so I can't move it to a more convenient location. But I can't give it away -- it's used. I don't want to throw it away -- there's nothing wrong with it. So it sits on the counter (still), waiting for me to make a decision about how to deal with a bottle of scrub.
This happens with lots of things. If I try something and don't like it, I have no problem giving it away, or even throwing it away. The dish washing liquid that did not discernibly cut grease is gone. But "perfectly good borax" from making my own laundry soap (it doesn't dissolve in my new washer) sits, waiting for a craft project. (For that matter, the leftover homemade soap sits as well, waiting to be used up. Not it's fault.)
I don't want to be the little old lady with stacks of old egg cartons, empty mayonnaise jars or cool whip containers. That's what this reluctance to get rid of "useful" things is, though. Keeping something that is not actually useful because it might be useful someday is how that little old lady got into that trouble.
So what do I do? Clutter is delayed decisions, so I need to make a decision about how to get rid of these things. I'll have to move the scrub to a dry(ish) spot in the shower. If it gets ruined from humidity, or dropped in the tub, at least it will no longer be cluttering up the counter. I can search Pinterest for other uses for borax, and washing soda. I may find them irreplaceably useful, and they may remain on my list of things I need. Or I may use them up and move forward. The soap will be a pretreatment for laundry with stains. I know my shower curtain could use the extra attention.
And so it goes. The useful things are the hardest for me to declutter, but if they aren't being used, they really aren't as useful as I like to think they are.