To reset a user password select the tab Manage Accounts on the left-hand side and then Vendors.
Once you filter your search for the specific vendor you're looking for you will notice under the column Users there is a blue highlighted user login that you will need to select.
Once you select the user a pop-up box will appear with their user information. To the right of Status you will see Reset Password highlighted in blue for you to select.
This will bring up another pop-up box asking you to verify whether you are sure you'd like to reset the password for this user.
To proceed simply select Yes and follow the steps to produce a new password.