Curbless on concrete slab w/ a concrete step up, does it need to be removed ?

[Brosuff]

Wanting to convert existing shower to a curcbless entry.
The existing shower is recessed into the concrete floor around 4 inches, but.. the place where there was a built in shower bench was sitting on top of the main floor.

To make this curbless will I need to cut this step up out and establish an edge against the back wall and start the slop from there ?