Looks like it. Not sure about France, but I believe that in Germany you have to remove the towball/hitch when not in use.
Tony.
No. Not the case in germany.
They'd usually be supplied with a nice clip on cap and the manufacturer recommends greasing the ball and covering it with cap. Then, if it's a removable hitch, you could, optionally, take it off in Winter or when it's not needed for extended periods.
But no. You don't need to take it off. For example a driver couldn't be expected to remove the ball if he parked his caravan and just wanted to nip down to Aldi for a bottle of antifreeze wine.