The Key to Great Leadership: Stop Overmanaging
The challenge for people being promoted is leaving behind the tasks they formerly had. This is for a variety of reasons. One, people being promoted are generally hard workers and good leaders, who are used to doing their job and not asking others to do it for them. It is a difficult transition to managing a team, and not being in the trenches all the time. Second, they may be managing their former peers, which always has the awkward potential. Third, they may not trust others to do things right.
However, to lead well, leaders can't overmanage. In fact, controlling bosses that are so involved in the details of a project usually end up stifling creativity and hurting morale. Also, the boss isn't able to oversee and manage plans for the future. Stepping back from the routine, daily jobs that others should be doing will allow the recently promoted officer to take a long view, and plan for real growth of his or her sector, while allowing others to learn to take on responsibility and prove themselves for future leadership roles.
Source - Forbes