Removing bricks set in cement/mortar is basically just a brute-force operation.
You can use any of the following methods:
- A short 4 pound sledge hammer and mason chisel to break things apart at the joints
- A full size 6-12 pound sledge hammer to just crush everything to dust and a pickaxe for chipping loose parts
- An SDS hammer with a chisel attachment to quickly break through the joints
- A full sized jack hammer would laugh at the endeavor
If you wish to minimize damage to the old brick underneath then choose option #1 or #3.
There will be leftover cement/mortar on the old bricks so you could grind that away with a diamond cup disc.
You could feasibly hire just about any general contractor and they will be able to remove the new brick.
A mason would be preferable because they would know how to make the end result look nice.