Managing dashboard and dashboard folder permissions
To manage the permissions of dashboards and dashboard folders, you must have Administer permission.
Users' access to dashboards is controlled through membership of roles. By default, role permissions that are granted on a dashboard catalog are inherited by the folders below it, and by the dashboards and objects that they contain. So, if a role has Edit permission on the dashboard catalog then all users within that role can edit every dashboard. You can manually add or remove permissions on a particular folder or dashboard. In doing so, you break the inheritance from the dashboard catalog. Typically you edit permissions on folders, not on individual dashboards or objects.