As the Administrator of an Organisation you can use the option of forcing an approval or rejection for any open approval request.
There are two things to keep in mind when thinking about forcing a decision:
If both are true for a particular approval request, you can force its approval or rejection.
After you select Force approval / rejection, a popup for leaving a comment will appear. This will find its way into the audit trail and prevent any future guesswork regarding the reason for doing so.