replacing element in copper boiler

hi i am trying to replace the element in an copper boiler i have drained the water from the tank in the loft through the hot taps but the tank still seems to be full is it safe to remove the old element any help much appreciated

You need to find some way to let air into the unit to finish draining the tank !

If you have some type of pop off safety valve what we call here a temp/pressure relief

valve, that you can pop open or remove to allow the tank to finish draining or open the

cold water taps in the house with the main cold water valve shutoff ?