I would recommend the Cohesive Zone Material (CZM) options for modeling delamination at a prescribed interface.
See Section 4.20 of the MAPDL Material Reference Guide (R2023-R1).
If necessary, you can also represent the concrete with one of the Geomechanical material options.
Refer to Section 4.11 of the MAPDL Material Reference Guide.
Refer also to some of the published example problems in the Technology Showcase Manual.
Below are two that might be good for a start:
Chapter 5: Delamination
Chapter 54: Reinforced Concrete Joint Analysis