Yes, you can remove the password from a PST file, but the method depends on whether you still know the existing password. Manual Method: If you remember the password, open the PST file in Outlook. Go to Data File Settings and choose Change Password. Leave the new password fields blank to remove the protection
Limitation: This only works when the current password is known. If the password has been forgotten or Outlook won’t open the PST file, the manual method won’t help.
Alternative Method: Recommended
If the PST file is accessible but the password can not be removed through Outlook, a password removal utility can be a practical option. In a case involving the restoration of an Outlook archive, we encountered something similar using Softaken Outlook PST Password Removal. What made things easier was that the tool removed the password without changing the contents of the mailbox and therefore the emails, folders, and attachments retained their original form. Since it works directly with PST files, Outlook did not need to complete the password removal process itself.