Move Contact from one stage to another in Sitecore Engagement plan

If you want to programmatically move one contact from one stage to another in Engagement plan, you can use below approach to do the same.

var manager = Tracker.Current.Contact.AutomationStates();
var currentState = manager.GetCurrentStateInPlan(new Sitecore.Data.ID("Engagement Plan GUID"));

if (currentState != null)
   {
     if (currentState.StateId.Equals(new Guid("{01139FA2-049C-46BF-A15A-654AF8DCF366}")))
       manager.MoveToEngagementState(Sitecore.Data.ID.Parse("Engagement Plan GUID"), Sitecore.Data.ID.Parse("Target State GUID"));
   }