Problem
Users may have forgotten to log out of QuickBooks after they're done for the day and you need to enter Single User mode as an admin.
Solution
1) Log into the company file as an Admin
2) Launch QuickBooks Messenger (Company menu > Chat with a Co-worker).
3) From the Actions drop-down, select Close Company File for Users.
4) Select the user whose QuickBooks you want to close.
5) Select Close Company File.
6) In the Confirmation window, select Yes.