Currently, BI Dashboard can be deleted using "Move to trash" option while in the dashboard screen and a popup shows "Only administrators can retrieve items from the trash." However as a Harness administrator, we cannot see the trash in UI and there is no API as well for us to view and recover deleted dashboards.
We have raised a bug https://support.harness.io/hc/en-us/requests/88042 for this but accordingly this feature request is needed to enable BI Dashboard Trash in UI and allow Harness Admins to restore deleted dashboards.