First, shut down your Mac and unplug the power cord along with other connected devices. Then use a damp, soft, lint-free cloth to clean the computer's exterior. Avoid getting moisture in any openings. Don't spray liquid directly on the computer. Don't use aerosol sprays, solvents, abrasives, or cleaners containing hydrogen peroxide that might damage the finish.
To clean the display on your iMac, dampen the cloth that came with your iMac—or another clean, soft, lint-free cloth—with water only, and then wipe the screen.
Don't clean the screen of your iMac with a cleaner containing acetone. Use a cleaner intended for use with a screen or display. Never spray cleaner directly on the screen. It might drip inside the display and cause damage.