Connection In Use
If a connection is used in reports or dashboards, it cannot be deleted.
How to identify it
When you try to delete it, a warning appears: "Connection is used in N reports."
What to do
- Open the list of dependent reports
- Remove the connection as a data source from each report
- Or replace it with another connection
- Then repeat the deletion
Alternative
If deletion isn't required, you can disable synchronization while keeping the connection and its historical data.