Removing mortar from drain

Hello everyone
I have recently took apart my entire shower down to the studs and slab. I noticed when i was finished the drain was covered in mortar or concrete not 100 percent sure but its really stuck on. Is there any easy way to remove this from the drain or do i just need to try and chisel it off. I was having a pretty hard time removing it and didn't want to damaged and existing plumbing. My shower is currently on a concrete slab.

 

I would use a small cold chisel and a very light hammer to tap on it, to see if that will chip it off. Go slow and don't beat the hell out of it.