I struggled with this when I first had Bara Vi and did ask how to get these things off on a UK HR site but no one replied so here is my contribution.
As the plastics on these Hella fittings are fragile no owner wants to break them. It’s a question of reasonably firm pull downwards to get the fitting over the lugs.
BTW the bulbs, at least on this ship are called festoon and are 41mm. I have led’s on order to replace these. The side lights are next to sort out, I have so far tried and failed to get the correct led lights. More when I manage. Oh, and I did order a red led for the over the table dome fitting, it has two filaments with different wattages and I will at least try with a red on one of the two.