If you have the Full permission on a document, you can delete the most recent version of the document or delete the document (and all its versions in all branches). Deleting a document version allows you to go back to a previously frozen state.
Deleting a version or a document cannot be undone.
When you delete a version or a document, you also delete all the objects it contains, and may also delete the target objects of shortcuts in other models. However these target objects are likely to exist in the versions following the deleted version. This has no impact in the repository, links between shortcuts and target objects are re-build after a check out, in the local workspace.
You can delete a document and all its versions in all branches by right-clicking the document and selecting the Delete Document command.