I would like to turn off auto leveling globally

So don't run the Fine tuning wizard. That requires the IR sensor.

All you can do to fine tune it is to adjust the screws.

 

You can't even (technically) adjust the Z offset with the autoleveling logic anyway since you have that disabled.
All you can do is manual leveling -- which is fine, but takes time and some patience

 

There is fine tuning a global Z offset and there is fine tuning the Z offset for autoleveling.
The Robo does the latter via the LCD and their wizard It stores a value that is fed into the autoleveling calculations for a level plane.
If Autoleveling is not used neither is that value.

I get what you want to do, but that wizard will not do it for you.

I manually level all of my printers and forgo the autoleveling. They are all a bit different in how that is accomplished. On the C2 I used shims on the corner posts.

 

Open a ticket with Robo and describe what you want for functionality. They may implement it at some point. Worth asking.

 

I do not have an R2 (I have a C2, 5 R1 machines and a few other brands -- no R2). However leveling the bed is not really much different regardless of which FDM printer you are using. I'd suggest starting with this video and having a look at how the bed mounts on your nmachine so you know what to adjust to change the leveling. The R1 series had screws on the bed corners that could be used, the C2 you just had to add shims (I used painters tape for layers of shims) there were no adjustment screws.