The way I handle it is by asking at the start if they want to keep anything and if they do it has to be out of the way the morning I start otherwise everything else I will get rid of. Anything good, goes with me by the end of the day, preferably in my van or on the trailer as it's removed so it's out of site and out of mind. I then get rid of it like I said I would, how I get rid of it is my problem then, good or bad. If you are the General Contractor of the project and have a contract, usually anything that has to do with the project has to go thru the G.C. btw I only get my utility knife out if I intend to use it...like sharpen my pencil, score a line, scrape some paint.....