wtmpClean is a tool for Unix which clears a given user from the wtmp database.
You can download it from the following link: https://packetstormsecurity.com/files/download/73994/wtmpclean-0.6.5.tar.bz2
Source: https://packetstormsecurity.com/files/73994/wtmpclean-WTMP-Modification-Tool.html