how to reset a ipad air completely

i just bought this ipad air at the gas station off this dude because he needed gas money and it has a password on it and atm i dont have a working computer

how do i completely reset the ipad to the settings when you first get it out of the box

without WITHOUT a computer i tried holding down the power button and the home button just keeps bringing me back to the begining to reenter the password

that i dont know about please help

please please help