When connected to a report server instance in SQL Server Management Studio, you can delete role definitions and shared schedules. You cannot delete reports, models, or other items on a report server. To delete report server content, use Report Manager instead. Or, if the report server is configured for SharePoint integrated mode, use the item management features in the SharePoint library that contains your content.
To delete an item in the report server folder namespace
In ObjectExplorer, expand a report server node. Navigate to the folder containing the item you want to delete.
Expand the folder.
Right-click the item, and click Delete.
When prompted, Click OK.