It's impossible for us to clean it up. If you tried to chase down a single fleck of paint so that you could scoop it up into a waste basket, you would definitely end up shedding a few flecks of paint along the way. that's just the way machines are.

Fortunately, LEO cleans itself. The atmosphere expands and contracts due to heating by the sun. That imparts just a tiny about of drag on everything in LEO. In the case of debre, it eventually causes it to reenter the rest of the way.

This is the reason that the ISS is at its current altitude. It's in the zone where the atmosphere is self-cleaning. Unfortunately, that means that left to itself, the ISS would eventually be pulled further into the atmosphere and burn up. To prevent this, the shuttle (and, I'm guessing, the progress supply ships) give the ISS a little boost every time they dock.

Basically, that's the best we can do. If we fly in space we are going to occasionally drop a nut or bolt or whatever. You either live with that reality or give up your intercontinental phone calls and news reports, live broadcasts of sporting events, advance warning of hurricanes, etc. etc.