I am using ArcMap 10.4.1.
I would like to turn off the "On the Fly Projection" capability temporarily if possible. Is it possible to do this and if so, how can I turn it off?
Simply don't add data to a dataframe that isn't in the same coordinate system that you want.
You can always open a new dataframe, add the data there, Project it to what you want, then move it back to the dataframe you want.
In ArcMap, "clear" the coordinate system. Data frame properties, Coordinate System tab. Click the globe icon (next to the star icon) and select Clear. That sets the map to "unknown coordinate system."
This is not possible in ArcGIS Pro.
If you instead want to turn off any geographic/datum transformations, you can set a transformation to "None" in ArcMap. Not working in ArcGIS Pro 2.2, but should work in ArcGIS Pro 2.3.
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