Make sure you provide the tools
I too am alone in the world of IT at my company. I am the sole IT person for a business that has multiple office locations across the state so you can imagine what my office looks like. Anything that comes under the title "equipment" is under my responsibility. It is definitely difficult at times to stay on top of it all with the limited time I have and so much to support, and as of yet I have not been given authority to purchase additional storage units despite asking for them several times over the last year.
My two biggest suggestions to managers and supervisors of IT teams that need "cleaning up" would be as follows:
1. Make sure your team has adequate storage for items in appropriate places.
2. Make sure you allow time for them to clean up during their busy schedule.