Transfer Lightning dashboard ownership when responsibilities change or the current owner leaves your organization. You can change the ownership of multiple dashboards at one time and can send an email notification to the new owner. Previously, you had to clone or re-create the dashboard to provide access to a new owner.
Where: This change applies to Lightning Experience in Group, Essentials, Professional, Enterprise, Performance, Unlimited, and Developer editions.
How: To reassign a single dashboard, on the Dashboards or Analytics tabs select Change Owner from the dashboard’s actions.
When someone leaves your organization, you can reassign all their dashboards on the Analytics tab. Select the dashboards, and then in the Manage Items menu, select Change Owner.
To notify the new owner, select Send email notification in the Change Owner window.
Transfer Lightning Dashboard Ownership (Generally Available) (salesforce.com)