Deleting, or wiping, the memory from your cell phone can protect your personal data, and prevent others from gaining access to your call history, photos, text messages, email account, calendar appointments, and more. Although the exact process for deleting your cell phone’s memory is different for each make and model of cell phone, there are basic guidelines you can follow to ensure that your personal data is wiped from the device; especially before you sell, recycle, dispose of, or donate the device to a charity.
Part One of Three:
Backing Up Important Data Edit
Back up your contacts. Before wiping your phone, you may want to back up your contacts list. You’ll be able to restore this list after you finish the reset procedure. If you’re logged into your phone with a Google (Android) or iCloud (iPhone) account, the chances are good that all of your contacts are backed up in the cloud already.
- See Back Up an Android Phone on the Google Cloud for instructions on backing up your Android contacts.
- See Back Up iPhone Contacts for instructions on backing up contacts on an iPhone.
Back up your iPhone in with iCloud. If you’re using an iPhone, you can use your free iCloud storage to quickly create a backup of your phone’s important. This will allow you to restore after the reset process, saving your messages, contacts, and more. 
- Connect your iPhone to the wall charger and to a Wi-Fi network.
- Open the Settings app and select “iCloud.”
- Tap “Backup” and then tap “Back Up Now.” You may have to toggle “iCloud Backup” on first.
- Wait while your iPhone backs up your essential data to iCloud.
Back up the important data on your Android phone. Your Google Play Store purchases (including apps) are all automatically saved to your Google account, but data that you’ve downloaded to your Android is not. This could include movies or music that you’ve downloaded directly to your device, documents you’ve saved, and more. There is no common back up tool for Android, but you can use your computer to quickly save any file on it. 
- Connect your Android to your computer using the USB charging cable.
- Select “Transfer media files” from the USB menu that appears in the Android notification panel.
- Open your Computer/This PC window on your computer and then open your Android storage. If you’re using a Mac, you may need to install Android File Transfer .
- Find the files you want to save. You can check your Downloads, Pictures, Music, and other folders for data that you may want to save. Copy these files to your computer to back them up.
Save your pictures. Your pictures may not be backed up automatically. You’ll want to make sure any pictures on your device are saved before erasing everything on it.
- See Transfer Photos from Android to Computer for instructions on backing up your Android pictures.
- See Transfer Photos from an iPhone to a Computer for several ways to back up pictures from your iPhone.
Back up your SMS (text) messages. Deleting your phone’s memory will wipe out all of the text messages you’ve received. You’ll be able to recover your email messages, but your text messages will need to be backed up.
- See Back Up SMS for a Samsung Galaxy Device to Your Computer for instructions that apply to all Android devices.
- Your iPhone backs up your messages to your iCloud account. When you log in after resetting your phone and restore your iCloud backup, the messages will be restored.