If not feeling confident maybe best to call in the expert, but it isn't a difficult job.
· Turn off power to cooker at fusebox.
· Unscrew front of cooker junction box, where lead goes.
· Use neon screwdriver to CAREFULLY check red or brown wire no longer lights up neon when tip is placed on it (AND NOT SHORTING OUT TO ELSEWHERE) and you have finger on OTHER END of screwdriver. (You can use a meter if you have one and know how to use it.)
· Having assured yourself all is well so far, unscrew the cable, preferably not shorting out anything as you go, and remove cooker lead.
· Screw junction box back up again.
· Job done. Fuse box to cooker may as well be left off as there is no cooker connected any more.