To remove a forgotten password from a PST file, you'll typically need to use third-party software designed specifically for this purpose, as Microsoft Outlook does not provide a built-in method for recovering or removing forgotten passwords. One common approach is to use the Advik PST Password Remover Tool  available online. These tools work by employing advanced algorithms to decrypt the password-protected PST file, allowing you to regain access to its contents. It's important to note that the effectiveness of these tools can vary, and some may be more reliable than others. Additionally, when using such tools, it's essential to exercise caution and ensure that you're downloading from a reputable source to avoid potential security risks. Once you've successfully removed the password from the PST file, you should be able to open it in Microsoft Outlook without any further authentication requirements.