Powerwashing is Google's term for performing a factory reset on a ChromeOS device.
If you have a Chromebook that's having problems, a powerwash might help resolve the issue. Before you get started, make sure that there's no data in the Downloads, Play Files, or Android App Data folders that you want to save; these locations will be erased during a powerwash.
Also, make sure that there's a nearby network you can connect to. If you powerwash your Chromebook without being able to reconnect to a network, you won't be able to use it again until you connect it to the internet.
1. Log out of any accounts that are currently logged in. You want to be viewing the ChromeOS logon screen.
2. Press and hold Ctrl + Alt + Shift + R.
3. Select Restart.
4. In the box that shows up, select the 'powerwash' option. It'll be in the bottom-right hand corner.
5. Follow the steps to set up your device and log back in.
And you'll be all set to go, with a freshly-washed Chromebook.