After retiring from playing, he continued his managerial career at then 2nd Bundesliga side Eintracht Braunschweig in 1988–1989. After two seasons as manager with Braunschweig he departed from the club, taking over FC Hansa Rostock in East Germany's NOFV Oberliga Nordost, previously known as DDR-Oberliga. As East Germany's Deutscher Fußball-Verband was to finally merge into Deutscher Fußball Bund after that, the 1990–91 season worked out to be the factor for those former DDR-Oberliga clubs to enqueue into the German soccer league structure. Under Reinders guidance Rostock won the final edition of the East German Cup (against FC Stahl Eisenhüttenstadt) and also grabbed the NOFV Oberliga Nordost title, which meant the team qualified to start in the Bundesliga in the 1991–92 season. Enjoying a fantastic start to the 1991–92 season, Rostock's form slumped massively and, with the threat of relegation rising, let the club sack him on 6 March 1992.
Just a month later he was back in charge of a Bundesliga outfit, successing Willibert Kremer at fellow relegation threatened MSV Duisburg. Reinders failed to avoid relegation with them. The begin of the then next season saw Reinders keep on at MSV, but on 21 October 1993, he left the Ruhr club to take charge of fellow 2nd Bundesliga side Hertha BSC. A job in which he lasted only five months before the faced the sack. It took nearly eight years to enable him a return to management in the top division of German football. On 25 October 2002, Eintracht Braunschweig of 2nd Bundesliga re-appointed Reinders as manager, he succeeded Peter Vollmann at the just re-promoted club. However, he could not keep Braunschweig up and was, following an uninspiring run through the lower Regionalliga Nord, sacked by them on 2 March 2004.
Reinders' next jobs were 1. FC Pforzheim, and then Brinkumer SV, a club promoted to the fourth tier of German soccer, Oberliga Nord, at the start of the 2005–06 season. Yet, he was not for long their manager, he resigned from his role mid-way through their campaign at a time when the club was only second from bottom with just seven points in the bank.