The BlackBerry OS has changed so much over the years that providing detailed steps to encrypt and reset every device is impossible. But the basic steps are quite similar to those of iOS and Android, and should roughly line up with the instructions below.
Go to Options, Security Options, General Settings, and set a password.
Then set Content Protection to Enabled. Choose the option to encrypt your address book as well.
Once that’s done, make sure your phone or tablet is plugged in, then follow these detailed instructions from BlackBerry to reset. Or just dive into Settings, tap Security, then tap Security Wipe.
Enter your password, confirm that you want to reset the device, tap the Wipe Data button, and wait for the process to finish.
Most older Windows Phone 7 devices lack on-device encryption. Windows Phone 8 devices do support encryption, but the average consumer can’t switch it on: Encryption must be enabled via one of two paid business-class services. That means device encryption isn’t an option for the average Windows Phone consumer, so you’ll have to go to a bit more trouble to securely erase your data.
To reset your Windows Phone, go to Settings, then About, then Reset phone. In Windows Phone 8, you’ll have to tap through two warning screens before deleting all your data.
Since you weren’t able to encrypt your old data before deleting it, you can then force the device to overwrite your old data by manually filling up the phone’s internal storage with nonpersonal files. Any small files that don’t contain personal data will work. MP3 files are a good choice, because most people have enough of them to fill up a phone.
Unfortunately, for older Windows Phones, you can’t just connect the phone to a PC and drag files over. For Windows Phone 7 devices, you’ll need to transfer the files via Zune software.
For Windows Phone 8, on a PC, you can drag files onto the device using Windows Explorer. For Macs, you can use the Windows Phone app.
However you get the music or other nonpersonal data onto the device, you’ll need to keep adding files until the phone is completely full. For added security, when the phone is full of music files, you can delete the files you added, then fill the device up again, and factory reset the phone a second time.