The moves came a little over a week before Buffalo opens the season at Detroit Oct. 2.
McNabb and Ruhwedel were both regarded as contenders to make the Sabres roster.
With two preseason games left, the Sabres (3-1-1) are still carrying nine defencemen. It's a group that includes rookie first-round draft picks Rasmus Ristolainen and Nikita Zadorov.
Introducing the new official NHL App, available for iPhone, iPad and Android smartphones and tablets. A host of new features and improved functionality are available across all platforms, including a redesigned league-wide scoreboard, expanded news coverage, searchable video highlights, individual team experiences* and more. The new NHL App on your tablet also introduces new offerings such as 60fps video, Multitasking** and Picture-in-Picture.
*Available only for smartphones
** Available only for suported iPads