Put protective goggles and gloves on before handling the descaling cleaner. Most descaling cleaners are made with chemicals that can be dangerous if they are inhaled or get on your skin.
Power the steamer off and let it cool down. Make sure all water has been drained from the steamer. Check the directions for your particular steamer to ensure you're following the correct procedure for leaving vents or compartments open or closed while deliming.
Open the deliming port and pour the deliming solution into the port. You may need a funnel to do this. Some solutions need to be mixed with water, so check the directions to make sure the solution is prepared properly. Once the solution is inside the deliming port, press the deliming button to start the cycle if necessary, or wait for the cycle to start by itself.
Allow the cycle to complete itself, or allow the solution to soak in the steamer for approximately an hour before the rinse cycle. Some steamers will automatically go into rinsing mode once the cycle is done. If your steamer doesn't enter rinse mode on its own, press the necessary buttons to rinse the steamer free of deliming solution before the steamer can be used to cook again.