you just have to lever or prise it out of its rubber seal -it may require some effort. Replace heater, use sealant when refitting rubber seal and ensure it is fully pushed into the recess in the backplate. Make sure the element locates into mounting bracket inside the drum.(look inside the element with a torch and you will see mounting bracket). This bracket ensures that the moving inner drum doesnt strike the element and damage it.
Repair and service your own washing machine. Go to www.2ndwave.co.uk/manual.html
dannyboy
January 2009