To reset your Outlook PST password, you can use the built-in settings if you already know the current password, or a specialized utility if you have forgotten it.

Method 1: Reset Using Microsoft Outlook (If you know the current password)

If you know your old password and simply want to change or completely remove it, follow these steps: 
1. Open Microsoft Outlook.
2. Click on File > Account Settings > Account Settings.
3. Switch to the Data Files tab.
4. Select your PST file from the list and click Settings (or double-click the file).
5. Click the Change Password button.
6. Enter your Old password.
7. To change the password: Type your new password into both the New password and Verify password fields.
8. To completely remove the password: Leave both new password fields completely blank.
9. Click OK to save your changes.

Method 2: Reset Using Recoveryfix PST Password Recovery (If you forgot the password)

If you have lost or forgotten your password, Microsoft Outlook cannot recover it for you. In this scenario, you can use a dedicated utility like Recoveryfix PST Password Recovery Manager. 
• No Outlook Required: It functions as a standalone utility, meaning you don't even need Outlook installed to unlock your files.
• Instant Unlocking: It can instantly recover, reset, or remove passwords regardless of their complexity, length, or encryption type.
• Batch Processing: It allows you to process multiple PST files at the same time to save effort.
• Universal Compatibility: The tool works across all Outlook versions (from legacy Outlook 97 up to Outlook 2021) and supports both ANSI and Unicode PST formats.