Would think its easiest removed by undoing hinges, top from inside van, bottom behind l/rear light, remove cluster to access, check strap remove circlip.
The back door on my van has had an off-van repairs made to it in the past, for this reason I am on the hunt for a good undamaged/repaired one as off vehicle pannel repairs often look perfect off of vehicle but when reinstalled the form/lines of panel may not match that of van, they are flimsy panels easily distorted with repairs, where rusted at bottom it has eaten factory line/fit, repaired off of van does not guarantee correct fit when reintalled as off van there are no panel gaps/fit to work to.