I have forgotten my password for the Credential Mnager. How do I reset it?
Do you mean "How do I reset my Administrator password for Windows Credential Manager?"
Depending on which version of Windows you're running, I would think you'd open the Credential Manager, in Credentials > User Accounts and Family Safety > Credential Manager.
From the list of already established credentials, you click on the arrow next to the one you want, and once it's revealed, you can Edit it, or Delete it. As always your mileage may vary, so have a complete backup just in case.