I show how I took off the original electrical box, referred to as new work electrical box, from a wall so I could upgrade it to a double gang old work box to handle an additional switch for the fan in the bathroom. Make sure there's no electricity present as you might get electrocuted if the circuit is hot. Also, make sure there are not water pipes near your outlet as this can cause a flood if you cut through one accidentally while trying to remove the electrical box.
