The former Newcastle manager, who signed Kevin Keegan as a player back in 1982, rejoined Kevin Keegan when the Messiah returned in January.
But Cox says he is happy to let his protege take the bull by the horns.
Toon Legend Leaves Newcastle ... Again!
Arthur Cox (born December 14, 1939 in Southam) managed a number of clubs including Chesterfield, Newcastle United, where he won promotion to the First division and introduced flair players such as Peter Beardsley and Chris Waddle.
He later moved on to Derby County, where he won two successive promotions.
Cox took Derby to 5th in 1989, but the unwillingness of Robert Maxwell to release funds for team-building contributed to Derby's relegation in 1991.
The following season saw Derby miss promotion to the Premier League, despite considerable investment by Lionel Pickering. He left in 1993, having failed to get Derby near the play-offs that season.
He has also worked as assistant manager at various clubs such as Sunderland A.F.C. and Galatasaray, and often as 'right-hand man' to fellow manager Kevin Keegan.
The two worked together at Fulham and then with the England national team. Keegan wanted to appoint Cox as England's assistant manager, but the FA would not allow it because he was over 60, so Cox was given a coaching position instead.
Cox resigned, along with fellow coach Peter Beardsley, following the departure of Keegan in October 2000.
They linked up again at Manchester City, where Cox was promoted from chief scout to assistant manager in April 2002, but retired in 2004, then returned to Newcastle last January.
Keegan also paid tribute to the man he described as a "true friend and confidante."
"Arthur Cox has been a wonderful servant to football and a great influence on my managerial career.
"I owe him so much, I hope he enjoys his retirement to the full.
"If anybody deserves a break and a bit of time with his family it is Arthur.
"I understand his reasons. He is a one-off and we will stay friends for life."