Pre-requisites
1. You should have an published extract from OBIEE data using Tableau Desktop. Refer to this step-by-step tutorial.
Modifying Credential options for a Published Data Source
After you have published a data source / workbook to Tableau Server , follow these steps to edit the credentials for the Data Source if user credentials are not embedded
1. Navigate to your published Data Source.
Note: If you have published your Data Source without embedding credentials it will shown under Authentication Section as "Not embedded in connection".
2. Click on Connections Tab.
3. Click the 
menu icon for the Data Source selected.
4. Click the 
menu to edit the credentials for the published Data Source.
Note: If you have published the Data Source without embedding credentials user will be on the "Prompt user for password if needed" option.
5. Server name, Server port and Username will be displayed by default (a corresponding environment that is used as the data source) if the workbook/data source is published correctly.
6. To change the Data Source to embed the password within select the "Embedded password in connection" option radio box.
7. Click "Change the password".
8. Enter the password in the text field for the specified user.
9. Click "Save" button to embed the password for the Data Source.