How do I descale the Barista Express?

When the CLEAN/DESCALE light is solid on (not flashing), descaling is required. Dissolve one Breville Descaling powder sachet into 34 fl. oz (1L) of water, fill the water tank, then press and hold the 2-CUP button and POWER button simultaneously to enter Descale mode. Press the 1-CUP button to descale the coffee component, then use the steam dial to descale the steam and hot water components, repeating the process until the tank is empty, followed by a full rinse cycle with fresh water. (Page 24)