Who's fault is it that you set up multiple Google Voice accounts, and didn't keep track of their corresponding user names and passwords?
If you do know the user ID and password, you don't need to start over; you should just be able to click on the SP on the OBiTALK dashboard, and then click the link "Replace Google Account Credentials", which will take you through the OAUTH 2.0 authentication setup again. You must be logged into the correct Google account in that same web browser to complete the procedure.