Create an extract and connect directly to that extract as a data source. There's no connection info in a TDE.
If you already have your workbook created, then you would do the following steps:
Extract your data from your connection.
Save that TDE somewhere.
Connect to a new data source of type "Tableau Data Extract"
Navigate to the extract and select ok.
Then "Replace Data Source" so that the extract is now your primary connection
Close your old connection that has the data source info with it.