Removing gas tank filler tube

My Haynes repair manual says 'lower the tank slightly and remove the filler
tube'. Unfortunately it doesn't say how to remove or reinsert the filler
tube and I am wary of pulling it out in case I never get it to seal again.
It looks as though the tube just pushes in with a rubber bush to seal it.
The alternative is to dismantle the bits of metal that the filler pipe must
get past if I leave it attached to the tank.

Has anyone any suggestions?

Thanks, Ted