No matter how well or how often you clean your oven, it's nearly impossible to remove all the grime without also removing the heating elements. Although it's vital to use proper caution and disconnect the power supply to the oven, it's not difficult to remove the heating elements so that you can clean properly. All you need is a screwdriver to disconnect the elements so that you can clean underneath where they normally sit before returning them to their place in the oven.
Disconnect the power to your oven either by unplugging it or switching off the appropriate breaker.
Test to make sure the power is disconnected by turning the oven or stove on and checking to see that it does not actually turn on.
Locate the screws holding the element in place. There should be two screws at the very back of the element where it plugs into the power source, and an additional three or four screws in a horizontal retaining shield in the center that holds the element in place.
Remove all of the screws by turning them counterclockwise.
Gently but firmly pull the heating element toward you and out of the oven. It will "unplug" from a socket at the back and you can remove it entirely from the oven.
Repeat with the other element.
Leave the electricity off while you clean and do not turn it back on until you have replaced the elements and screwed them back into place.