A club statement confirmed that the 50-year-old has joined physio Paul Chappell in dpearting the Dingwall club "as part of a restructuring of the football staff".
Copper, a former Aberdeen and Rangers midfielder, managed County between 1996 and 2002. He returned as assistant to Derek Adams in November 2012.
"I would like to thank Neale and Paul for their assistance while at the club," said the County manager. "I wish them success in the future."
Cooper's son, Alex, remains in the first-team squad.