Brick pillars gone now what?
It sounds like your 1" pads may be non-shrink grout. If it is different in texture and color, it should pop off the concrete, and yes grind off the metal bar with a thin cutting wheel on a small right angle grinder. If the surface is to be part of the finished job, I would consider chiseling down around the pin with a neat hole or use a core drill, to cut it off below the surface. Then you can fill the hole with an expansion concrete mixed with sand and pea gravel to mimic the surrounding finish as best as possible. You could wipe it off a little with a damp sponge to expose the aggregate a little after it has initially set to mimic ageing a bit. Be careful with this step though.