You are very funny wabbit
You cannot turn openGL ON or OFF, it is nor a process running on your machine, it is rather huge set of hardware 2D rendering procedures called by the software itself.
If Hexagon has no other way to output to it's window then calling openGL to do it, then you are stuck with it.
Carrara, for example, has other way of doing this (software renderer) hence you can choose between those two...