The most important step in selling or giving away your Google Pixel is to completely wipe it of all your data with a factory reset so the new owner can start using your Pixel with factory-fresh software. This process is extremely easy:

Step 1.  Open the Settings app on your Pixel

Step 2.  Click on the System tab

Step 3.  Click on the Advanced menu

Step 4.  Click Reset Options 

Step 5.  Select Erase All Data

Step 6.  Select Erase All Data 

Your Google Pixel will now begin resetting. Make sure it’s plugged into a charger for the duration of the reset process.