How do I forget or change the username and password for file sharing? I connected my MacBook (macOS 10.13 if it matters) to my Mac Pro fileshare using the username foo and the password. I tell Finder to save the password.
I want to disconnect from that server and login again but this time with username bar and bar's password.


Here's the problem: as soon as I press the Disconnect button in the Finder on my MacBook, it immediately reconnects as user foo. It does not stay disconnected. 

How can I connect to an existing server with a different username and password?
Go to the Finder’s Go menu and choose Utilities
Select Keychain Acces
Select the Login Keychain then select the network password or internet password for the printers and/or shares.
Hold down the “control” key and click the keychain entry. Select Delete.


Now, access your network resource (printer or share) and re-enter your new username and password when prompted.