Rear wheel bearing seal replacement - Tube Axles
It is not necessary to remove the brake backplate and seal housing from the axle assembly - simply withdraw the inner cone (on which the hub mounts and the seal runs) over the halfshaft.
Do this carefully so so as not to damage the seal surface - use polygrips with appropriate padding between the jaws and the cone.
Once that is out, there is enough gap to insert a large screwdriver behind the seal and flick it out.