Hi

I have a Doblo 1,3 disel from 2010, but I I need to remove the longitudinal bars, since the blocks must be repainted.

But I can not get them off.

Are there some one there can help ?

Looks like you prise the discs out with small flat blade, then you should see the bolts.
Can see 2 discs in photo should be 3

I have tried, but I can not get them out, and are afraid to destroy them.

It feels like there is a kind of spring underneath.

Try a thin flat blade screwdriver on both sides, expect they are a tube shape in the hole rock the thing from side to side, levering up GENTLY, you do not want to go in deep with the levers. ( A bit of tape or rag where the levers rest on bar will help to protect it)
Have never had a go at roof bars but the roof rack bolts fit in those holes on vans, vans have plastic cr**y screw things that break when you try to remove them, Transit & other make foot well plastic mats screws are hidden by same looking things