To reset or remove a password from an Outlook Personal Storage Table (.pst) file, the method you choose depends entirely on whether you currently remember the existing password. 

Method 1: Resetting via Microsoft Outlook (If you know the current password)

If you already know the password but want to change or completely clear it, you can handle this directly within the classic desktop application: 
1. Open Microsoft Outlook.
2. Click on File > Account Settings > Account Settings.
3. Switch over to the Data Files tab.
4. Select the password-protected PST file from the list and double-click it (or click Settings).
5. Click the Change Password button.
6. Enter your current password in the Old Password field.
7. To change the password: Type your new password into the New Password and Verify fields.
8. To completely remove the password: Leave both the New Password and Verify fields completely blank.
9. Click OK to apply the changes. 

Method 2: Resetting if you Forgot the Password

Microsoft Outlook does not provide a built-in recovery mechanism to bypass or retrieve a lost PST password. If you have lost or forgotten your credentials, standard manual methods will not work, and you will need to utilize specialized automated utility software to unlock the file.

Using Recoveryfix PST Password Recovery Tool

The Recoveryfix PST Password Recovery tool is a dedicated professional program built to instantly crack, reset, or remove passwords from encrypted Outlook PST files without needing the original credentials. 
• How It works: It functions as a standalone utility—meaning you do not need Microsoft Outlook installed to use it. You simply download and launch the tool, upload your locked PST file, and execute the automated process. The software will either completely strip the existing password or safely generate a functional fallback key that unlocks your data. 
• Key Strengths: It safely supports both legacy ANSI and modern Unicode PST formats across all Outlook iterations (including Office 365). It handles complex, highly secure, or multilingual passwords without risking file corruption. It features a batch mode to unlock multiple PST files simultaneously and preserves your precise emails, attachments, and original folder hierarchies intact.