Queries available for List Reports, and Detailed Reporting queries for pivot tables, cannot be deleted from within Report Designer. They do not appear in Query Workspace.
SuccessFactors Analytics - Report Designer
Queries in the Detailed Reporting section of the selector are editable in the Detailed Reporting or Advanced Reporting tools. Report Designer only allows editing of a query within a report component, which does not feed back to the saved query. Query Workspace is only for queries based on Workforce Analytics data.
Go to Detailed Reporting or Advanced Reporting, and open the folder of saved queries. Once you see them, you can select them and edit or delete as necessary.
KBA , LOD-SF-ANA , Analytics & Reporting (Ad Hoc, ORD) , Problem