You can delete only those dashboards that you own. If you are a member of the SYSADMIN group, you can delete any dashboard.
You cannot delete the default dashboard. To delete the default dashboard, you must first configure another dashboard to become the default dashboard on the General tab of the User Preferences dialog box.
If you are deleting a dashboard whose dashparts are shared with other users, you must first revoke their access to the shared dashparts using the Access Control to Dashparts dialog box.
For more information, see Dashboard Overview.
To delete a dashboard:
On the Navigation menu, click Dashboards then select the dashboard that you want to delete. You can also use the Dashboard Search dialog box to select a dashboard.
On the Dashboard toolbar, click Dashboards ยป Delete Current Dashboard.
When asked if you want to delete the current dashboard, click Yes.
Learn about the Dashboard toolbar
Configure access control to dashparts
Configure access control to dashboards