Donald was appointed in June 2011 as part of Gary Kirsten???s management team and continued in the role under Russell Domingo from August 2013.
A former fast bowler for South Africa and part of the first national team in the post-apartheid era, Donald was his country???s leading wicket-taker at the time he retired, with 330 Test scalps.
The 48-year-old, who helped take South Africa to the World Cup semi-finals, said it was ???the right time to move on???.
???I have had some time to reflect after the World Cup and have come to the conclusion that the time is right to move on,??? Donald told the Cricket South Africa website.
???It was always a big dream of mine to work in the South African cricket environment after my playing days and I was incredibly honoured to be given the opportunity.
???The last four years have been the best of my life and being involved with the Proteas in the 2015 Cricket World Cup was a goal I had set my sights on.
???I was blessed to have worked with the best bowling attack in the world over a four year period and leave with fond memories and experiences, particularly getting to the top of the ICC Test rankings.???
Cricket South Africa said a replacement bowling coach would be ???considered in due course???.??
South Africa next play Bangladesh in July.