Any Advice From the Floor Guys

[BigRichard]

I am starting to tear up my bathroom which had marble flooring. I have done ceramic tile before and it seems like they used way more thinset than what was needed here. It seems to be cracking off in little bits as I get my pry bar to get underneath of it instead of the entire tile coming up. Any suggestions here? Will I be able to get up that thinset off of that cement board? I was almost thinking that I will need to cut up all of that cement board too and replace with new for the tile I am going to put down.