The electric cooktop in your home may eventually need replacement. It may die, you might need to replace it because you are remodeling your kitchen and need new decor or you may just want to upgrade to a better appliance. In any case, you must uninstall the existing electric cooktop before you can put in a new one. Many appliance stores offer free installation when you purchase a cooktop from them, but they will charge you to uninstall your existing cooktop and dispose of it. Being able to uninstall your own electric cooktop can therefore save you money.
Open your home's electrical panel and find the switch for the electric cooktop. The breaker switch will be a double switch dedicated solely to the cooktop, and should be labeled as such. Push the switch to the off position -- the breakers are coupled, and both of them will go off at the same time. Be sure not to touch any of the other breakers.
Open the cabinet doors below the cooktop. Locate the electrical connection box attached to the bottom of the cooktop. Use a screwdriver to remove the screw that holds the cover to the electrical connection box in place. Remove the cover to the electrical connection box.
Attach the electrical voltage detector to ensure there is no active electrical voltage in the wiring in the box. Remove the wire nuts from all connections in the box. There should be three groupings of wires--one white set, and two colored, usually black and red or black and black. When the wire nuts are removed, separate the wires to ensure they are not touching each other or any metal surface.
Remove the power feed wires from the box. These wires will be the ones coming into the box from an external source, not coming from the cooktop itself. When removing the wires from the box, pull them through the entry hole carefully, making sure to not touch the wires to any metal surface while removing them. After removing the wires from the connection box, screw the wire nuts back onto each of the wires.
Cut through any caulking on the edge of the cooktop, using a razor knife. Check under the counter for brackets holding the cooktop in place. If there are brackets, use the screwdriver to loosen the screws and remove the brackets.
Slide a putty knife under the edge of the cooktop. Use the putty knife to lift the edge of the cooktop until you can get your fingers under it. Lift the cooktop out of the hole in the countertop.