If you are in OJS 2.x, your version info should be in About > About this publishing system.
If you check the Summary page of the submission, as Editor you can assign any editor (including yourself) as editor of the submission.
You can also archive the submission from that page.
If the article has been published, it has already been archived, which means you won't be able to archive it again.
To remove published submissions, you must first remove them from the issue their published, archive them, then, in the Archives, delete the submission.
If you are not able, maybe your are login in as a section editor, who has full powers only on the submissions (s)he is assigned to.
If you are, you SHOULDN'T be able to even see that submission...
You may also be running into a database inconsistency issue here...