Yes, it should be safe to destroy the cube. You might need to do this from a TI process with the CubeDestroy TI function.
The annotation should be automatically recreated with the correct number of dimensions when a user tries to add an annotation. I can't remember is the first user to add an annotation needs to be an admin (since a cube is being created). I believe that CubeSecurity also applies (make sure users that need to create annotations are in a group with WRITE access to the new annotations cube).
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Stuart King
IBM Planning Analytics Offering Manager
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