How hard is it to temporarily disconnect the main swing arm pivot (Orbea oiz)?

I built this bike myself (bought just the frame) but the frame itself came assembled. I‘d like to disconnect the swing arm so I can better position a foam piece that goes in there that acts to stop mud, debris, etc from getting in. I’m just concerned about all the little pieces coming loose and then it being too difficult to put back together. Your advice/tips would be greatly appreciated!