There should be a white dot at one end if it's the right way up. At the other end there should be a small black fabric tag, just pull that to yank the tray out. Figure 3 in the instructions (labelled 'remove the bracket') shows that tag being gripped.
P.S. There's nothing in there that I would call a 'bracket', I'd call the part a 'battery tray' or a 'battery holder'.