Grafana - This data source was added by config and cannot be modified using the UI

I’m seeing this message in Grafana when looking at a data source:
This data source was added by config and cannot be modified using the UI. Please contact your server admin to update this data source.
I’m the admin and don’t know how to update the data source. I’ve remove the config and i’m not sure why this data source is still listed. Does anyone have any details?

Connecting to the MySQL database and doing a delete worked.