I've seen several people ask what "wiping a server" means and whether that phrasing means anything more than simply deleting files.
"Wiping" a server doesn't necessarily have a strict definition; however, it implies more than just deleting files. When you delete a file from your computer, it isn't really gone. In essence, the drive just knows it can overwrite that data. With the proper equipment and software, deleted files can still be recovered as long as they haven't yet been overwritten by new data.
Wiping implies either a secure delete, or formatting of the server's hard drive. In a secure delete, files are deleted, and the hard disk sectors that housed them are immediately overwritten with meaningless data. This process of overwriting the sectors makes the files extremely difficult, if not impossible to recover.