In Classic UI, when a user without activate permission deletes a page, the deleted page disappears from Site Admin UI  immediately.
However, the page still exists until another user with activate permission approves the deletion through the workflow instance triggered by the delete action.
When the another user or admin terminates the workflow instance in workflow console , the page remains in publish while the page is no longer visible in siteadmin.
How do you delete the page completely in the above situation?
Delete the page from touch UI, the page remains visible until the deletion workflow completes.
Note: The deleted page has properties of the page node/jcr:content, deleted[Date] and deletedBy[String]. If those properties are removed, the page becomes visible and can be deleted again.