I started off with a Samsung Focus, and recently moved to a Lumia 900. I would now like to sell my Focus.
How should I go about making sure that the phone has been properly erased of all personal information so that the purchaser isn't able to get anything off the phone, like Contact info, etc?
Use the reset option of the phone.
It can be found on:
Settings > About > Reset your phone
As it says on the image, it will make the phone as you have found it on the first ON. It will not only delete all apps and photos, but will delete all email accounts and emails, linked accounts and profiles and everything that is not from the Phone itself.
I have tested this with the company Nokia Lumia 800 (in the picture as in my next company I got another one) as I had to return when I left the company and works fantastic, no trace of you will be found there...
Worst case scenario and last resort, you can hard reset the device through the bootloader. Each device has it's own way to enter the bootloader menu.
The most common way (with htc devices) is to power down the device. Hold the down volume button in, then press and hold the power button until the bootloader is displayed. Another variation is to press and hold both volume up and volume down at the same time (not an easy feat), then press the power button until the bootloader displays.
Once the bootloader menu appears there will be a hard reset option. Use the volume down button to navigate the menu, and volume up to confirm (there will be instructions once you enter bootloader mode).
[If anyone knows how to enter bootloader mode on different manufacturers, please leave a comment below]
