Select the "Convert" option when displaying the SQL, NOTE: once the report SQL has been converted to manually SQL it cannot be converted back
1. Open the report in Report Studio
2. From the 'Query Explorer Bar' select the report query you want to modify
3. In the 'Properties pane', select the elipse button next to "Generated SQL/MDX"
4. When the SQL window appears select the "Convert" button near the bottom of the window