To factory reset a Blu Android phone, start by opening the 'Settings' menu on your phone. Scroll down and tap on 'System', then select 'Reset'. You'll see an option that says 'Factory data reset'. Tap on it. You'll be prompted to enter your PIN, pattern, or password for security reasons. Once you've confirmed your decision, your phone will begin the reset process. Once it's done, your phone will restart and you'll be greeted with the setup screen, just like when you first bought it.