It is preferable to unplug it but it is probably hard wired so that will not be possible.

Turn the breaker off.
Then try the stove for any signs of life.

I cannot find a wiring diagram for this unit so cannot give an alternative method to checking that both sode of the line have shut off.

Remove the door from the unit so that you do not have to reach in too far.
Undo the screw/s holding the element to the back of the oven cavity.
Now gently pull it into the oven.
Try not to touch the oven frame/case with any part of your body.
Also a good idea to wear gloves when doing this, will give you some isolation.
When you get it into the oven use a meter to measure from each element connection to the units frame and across the element for voltage.
If all are 0 volts then you know for sure that the power is off.
The above may be overkill but I do not trust breakers.

It is a good idea to clip something (clothespin etc.) onto the wires so that they do not disappear into the back of the unit before you get the new element in stalled.