Step 1 is to create back up copies of any files you want to keep. At a high level, you have three paths:

• The fastest (and often cheapest, if not free) option is a Cloud Drive. Simply upload your files, photos, and anything else to OneDrive, Box, Dropbox, or Google Drive.
• Cloud-based backups: whereas a Cloud Drive lets you upload files on a one-off basis, a backup service will regularly take a backup copy of your designated files. 
• If you prefer a drive you can hold in your hands, you can also copy your files to an external hard drive. You’ll have to buy a drive; once you have it, simply drag your Documents folder (or any other desired files & folders) over to the external drive.

Step 2 is to remove any connected applications, especially those that sync files to or from your device. Examples include:

• Sign out of Cloud Drives such as OneDrive, Box, or Dropbox
• Deauthorize iTunes, so that future purchases don’t continue to download to the device you’re recycling.
  • Open iTunes
  • Select the Account menu, then Authorizations > Deauthorize This Computer.

Step 3 is to encrypt your data. Not all Windows devices support this; if yours does, we recommend it.

• Windows 10: Click Start > Settings > Update & Security > Device encryption
  • If Device encryption doesn’t appear, it’s not available for you
  • If Device encryption does appear and is turned off, click Turn on
• Windows 8.1:
  • Summon the Charms Bar by pressing Windows+C or moving the mouse to the top-right or bottom-right corner of the screen
  • Click Settings > Change PC settings > PC and Devices > PC info
  • Scroll down to the section Device encryption
    • If Device encryption doesn’t appear, it’s not available for you
    • If Device encryption does appear and is turned off, click Turn on
• Windows 7:
  • Only Windows 7 Enterprise and Windows 7 Ultimate offer encryption, through a program called BitLocker.
  • Click Start > Control Panel > System and Security
    • If BitLocker does not appear, it’s not available for you
    • If BitLocker does appear, click Turn on BitLocker.

Lastly, step 4 wipes your data by resetting Windows.

• Windows 10: Click Start > Settings > Update & Security > Recovery > Get started
  • Select Remove everything
  • Follow the on-screen instructions to restore Windows to a factory-fresh state.
• Windows 8.1
  • Summon the Charms Bar by pressing Windows+C or moving the mouse to the top-right or bottom-right corner of the screen
  • Click Settings > Change PC settings > General
  • Find the Remove Everything and Reinstall Windows section, then click the Get Started button
  • Follow the on-screen instructions, telling the program to clean your hard drive
• Windows 7: print or write down these steps, so you can reference them while your computer is off:
  • Reboot your computer
  • While it is turning on, press and hold the F8 key
  • At the Advanced Boot Options screen, choose Safe Mode with Command Prompt, then press Enter
  • Log in as Administrator
  • When the command prompt appears, type in rstrui.exe
  • Press Enter
  • Follow the instructions to start the Restore process