You can remove a password that you previously set on a Personal Folders file (.pst) (Personal Folders file (.pst): Data file that stores your messages and other items on your computer. You can assign a .pst file to be the default delivery location for e-mail messages. You can use a .pst to organize and back up items for safekeeping.) by doing the following:
On the Go menu, click Folder List.
In the Navigation Pane (Navigation Pane: The column on the left side of the Outlook window that includes panes such as Shortcuts or Mail and the shortcuts or folders within each pane. Click a folder to show the items in the folder.), right-click the top level of the .pst file.
Click Properties.
Click Advanced.
Click Change Password.
Note Outlook.pst is the default name for an Outlook Personal Folders file. The name you see might be different.
In the Old password box, type the password that you set on the .pst file.
Leave the New password and Verify password boxes blank.
Click OK.
