This is an easy one … but I forgot enough times that I needed to add it here.

• Turn off your Nexus device
• Press and hold the Volume Down and Power keys at the same time for about 7 seconds
• An image of an Android lying on its back will appear
• Press the Volume Down key twice – you’ll see “Recovery mode” appears on the screen
• Press the Power key to restart in “Recovery mode”
• An image of an Android and a red triangle will appear
• Press the Power key and Volume Up keys simultaneously (it may take a few tries)
• Use the Volume keys to scroll to “wipe data cache partition” and press the Power key