Why the change? I need to see the whole space and without the pink glow ideally. You need to see how the existing mantel is attached to remove it and I can't tell from the pic. As for german schmear have you done it before ? I think as a first time DIY I would just paint the brick since the schmear can really look bad if not done right.

It looks like a smooth surface brick which may not take a schmear the way it's supposed to. You might have to paint it instead. If you're doing it yourself, be sure to research the correct way to paint brick and use the right product. How are those corbels attached? Are they just screwed in to the brick? If so, remove them, patch the holes and painting over the brick should take care of it. A better quality picture with a close up of the brick and corbels might get you better advice.

Thank you. The brick is traditional brick that is rough. As for the corbels I’m not sure as the holes are plugged where hardware is