Now for the trickiest part of this job. There is one more 13 mm bolt to remove and it is on the bottom of the bracket, hidden from view. It's up inside the bracket in the area highlighted.
Reach down and feel for the bolt head first with your hand to get an idea of its location, then use a long extension with a wobble on the end and a 13 mm socket to loosen and remove this bolt. Note that there is a washer on the bolt - try not to drop it as you remove it.