fix

University/DatabaseImplement/Implements/DisciplineStorage.cs

@@ -66,7 +66,7 @@ namespace UniversityDatabaseImplement.Implements
             var element = context.Disciplines.FirstOrDefault(rec => rec.Id == model.Id);
             if (element != null)
             {
-                context.ExaminationResults.Remove(element);
+                context.Disciplines.Remove(element);
                 context.SaveChanges();
                 return element.GetViewModel;
             }