Shut down the iMac and unplug all cables
Disconnect any external devices
Use a soft, dry, lint-free microfiber cloth to wipe the screen and exterior
Dampen the cloth lightly with water if needed
Wipe the screen gently without pressing hard
Clean the stand, back, and ports with a dry microfiber cloth
Use a soft, dry brush or compressed air for dust in vents and ports
Avoid spraying liquid directly on the iMac
Avoid abrasive cloths, paper towels, and harsh cleaners
Avoid getting moisture into openings
Let all surfaces dry completely before plugging it back in
Reconnect cables and power on the iMac