The outer most plate is the brake line bracket, under that is the cap that closes the end of the axle carrier to retain the suspension link.
Once you remove the remaining bolt, both pieces will come off. You will have to remove the wheel, caliper and rotor to get enough working room. Can't recall what else you might have to remove right now. Once the cap is off you can pull the link out of the carrier and rotate the carrier up.
Once you get the cap of, you might find you have enough bolt sticking out to get a decent purchase with a set of vise grips. If so, drilling and tapping wont be necessary, but you might want to get a good bottoming tap to ensure the threads are true.
Hope this helps.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.