No, it is not possible to edit the dates of your running sprints. Agile methodology helps users to plan and prioritize the deliverables even before the work is started. The team estimates the work items for the sprint and schedules the duration of the sprint during the sprint plan meeting. After the sprint is started, modifying the dates can cause inconsistency and a loss in the tracking process. Learn in detail why updating the sprint duration is not advised. 

• Navigate to sprint details, complete the sprint, move the pending work items to another sprint, or start a new sprint.
  
• Replan the sprint, set the duration, and start the sprint from your plan mode.