If this is what you bars are held in place with, these can be removed with a nail
photo courtesy Amazon/Estwing
The larger mushroom part of the pin assembly is soft lead, the pin in the center is a much harder metal. Drive the angled end of the nail puller forks around the center pin by digging into the lead "head", it will yield, and allow the harder center pin to be guided into the notch of the nail puller. Once a firm hold has been achieved, lever the head of the pin out a little. The larger part should and MUST remain in place. Once the center pin is pulled perhaps a 1/4", get a new hold with the nail puller and pull it out, perhaps as much as a 1/2". This will allow you to grip it with a pair or pliers and twist and pull out straight to remove the center pin completely. Do this with all 4 corners.
Next vibrate the bars at each corner by tapping the end of the horizontal bars to the left and right, and up and down if possible with a hammer. This should loosen the grip the lead had. The grab a corner and tug a little on each one, not enough to remove it completely, but enough to get it to move in and out. From there you should be able to grab the lead part with the pliers and finish removing the lead part by pushing the bars to the wall while pulling out the loosened pins. And, there may be a chance it will all come off easily after the tapping with the hammer. And I do mean tapping, no hard hitting, it simply needs to vibrate the lead parts after the pins are gone.
I use this very same technique to remove signs attached to concrete walls which is much more durable than some types of brick. For the signs, I pulled the pin and ripped out the lead part with no damage to the concrete. The TLC I wrote about should get past any fragile or brittle brick you may have.