Those pieces are separate, though they move together when you change the magnification. Rotate the eyepiece free of the locking ring by rotating it counterclockwise beyond the point where the magnification adjustment stops/locks out, then maximize the magnification. Adjust the parallax (infinity works best) so that the optic is not focused, then adjust the eyepiece until the reticle is clear. When you have the eyepiece set correctly, the reticle will always be clear regardless of parallax or magnification. Once the eyepiece is set, preserve the relationship between the eyepiece and the magnification ring, and tighten the locking ring.
ETA: Manuals are free & located here:
https://www.nightforceoptics.com/download/