Defeating Range Superiority

“A unit may negate the opposition’s range superiority with a successful Advance or Flank manuever. See the unit action descriptions for details.”

How is this accomplished since there are no associated details underneath Advance or Flank?

There’s nothing that needs to be done other than completing either of those maneuvers successfully.

That is rang superiority is maintained until a unit advances to or flanks the unit with the range superiority. When the maneuver is successful the range superiority disappears.

Least that’s my understanding of it.

Yup. The details are about winning the maneuver. No other process necessary.