@charitymunoz to tell the truth I’ve asked myself this a lot too, my office is way too cluttered and I make it worse but forgetting to recycle the Dr Pepper bottles on my desk. As far as old sketches and art stuff goes though I have a few places I use for storage.
For pencil sketches I have a shoebox filled with around 10 sketchbooks and around 1000 index cards. I’m probably not going to do anything with most of them but it’s nice to just doodle. I keep my digital stuff on a 100gb thumb drive. I don’t need that much space but it’s good to have just in case.
I hope that helps with some storage ideas. We often have to create a ton before we get anywhere with art so having a place to put it all helps you see how much you are growing.