I don't know which OS your tablet uses... perhaps Jelly Bean. If so, if you push the Power button and the "Power Off" option shows up on the screen press the selection of "Power Off" and hold your finger down on it until a pop-up screen shows a selection of: Boot into "Safe Mode". Choose that and what happens is it boots up with no applications loaded. You should then be able to access the "Settings" and then choose "Factory Data Reset" option.
I could not find a manual for your model of tablet, so a lot of what I've stated is based on using Jelly Bean OS and such.
Will the above reset work on a Supersonic SC-772kt tablet? I hope so cause a customer purchased a used tablet that had a password on it and won't let her child use the tablet without the password. Would love to be able to help her create a new password and use the tablet. Any help would be appreciated.