Purpose of deleting internal PAD
So two schools of thought on this.   One removing the internal pads can increase yield for the PCB process.  It gives them a lot more clearance around the holes they're going to drill for instance.  Also pcb houses feel it extends their drill life not having to drill through all that copper each time.

On the SI side of things if you're trying to build a controlled impedance via structure, having all these internal pads doesn't help so another reason to remove them.   You might also remove them if you plan to back drill.

On the other side of things some people, and military standards, believe that leaving the pads there helps strengthen the via structure itself and improve long term mechanical reliability.

Personally I remove them.