Deleting Whiteboard Content and Slide Annotations
You can use the Erase Tool to delete lines, shapes, and text that you have drawn or entered on the whiteboard or for a slide annotation.
To erase one item, click the Erase Tool 
, and then click the item you want to delete. Small squares, or handles, appear around the item before you delete it.
You can also delete everything you have created on the whiteboard or all annotations on a single slide. (Deleting annotations on a file, does not delete the contents of the file or the file itself.) To delete everything on the whiteboard or all annotations on a slide, click the 
.