Raised bed 10x2 meters x 60 cm removal cost?

I would leave it as it is, whether with grass or flowers/bushes. That is what gives this edge strip structure and makes it look valuable. You won’t get more grass than the thickness of the retaining wall, about 20/30 cm, anyway. Yes, and then there is the hedge, which is probably raised as well. If you leave something standing there, you won’t gain any space. In addition, the roots could suffer and the privacy screen will turn brown in the long run. From my own experience, I know that you cannot create a play or sitting garden from an ERH or DH strip. Otherwise, I would advertise it for self-pickup :)

My thoughts on the pictures: I would be glad about such a clear, clean boundary. Much less dirt is brought into the house. Leave the wall standing for now, cut back the hedge much more and design the area according to your wishes. Maybe then you'll realize that removing the stone wall does not bring any gain in space and is not necessary at all.

Hm I would at most remove the piece next to the trampoline and somehow make it a bit nicer so that (children) can easily walk up there. Apart from that, I would remove the terrible hedge, I think IT gives a cramped impression...

cut the hedge back much more

If I'm not mistaken, that's Thuja. If you cut "much more" back, it's done for. Which on the other hand wouldn't be the worst thing ;) I would also leave the step there and try to integrate it into the design. There is nothing more boring than flat lawn gardens, no matter how big or small.