Not illegal to remove if its 'faulty'
*cough* loophole *cough*
Seeing as most of the valves, filters and hoses will be clogged, missing or incorrectly routed anyway, far better to remove the lot. I always do.
But, when you do, make sure to remove everything, not just a few bits and pieces.
And don't just disconnect... remove.
Plug any holes you have after doing so.