You can exclude an element from a group instance so that it is not visible in the view, and you can move an element from a group instance to the project view.
Excluding elements from a group instance may be useful when, for example, you place a hotel unit group defined with 4 bounding walls adjacent to a similar unit, and the walls overlap. You can exclude the overlapping wall from the group instance. If the excluded wall is hosting any elements (for example, a wall-hosted tub or a door), Revit attempts to rehost those elements on the remaining wall.
You can exclude an element using any of the following methods:
When elements are excluded and are not visible in the project view for a group instance, they are not included in schedules.
Excluded elements can be restored to their group instances.
To exclude an element from a group instance

 ) to exclude the element, or right-click, and click Exclude.
) to exclude the element, or right-click, and click Exclude. 
  The element is excluded from the group instance, and hosted elements are rehosted as necessary.
To move an element from a group instance to the project view
To restore an excluded element to a group
 ) to restore the excluded element, or right-click, and click Restore Excluded Member.
) to restore the excluded element, or right-click, and click Restore Excluded Member. 
To restore all excluded elements in a group
 Group panel
Group panel
 (Restore All Excluded).
 (Restore All Excluded).