you can UNINSTALL messenger, and remove the folder from  C:\Program Files\Yahoo!\Messenger  ~ this will remove all the custom settings you have in place. ( well most of them) 

But Roving_Cowboy was wondering about editing the REGISTRY to remove those messages...   so we decided to look around......  the quickest way we found to search for those messages was by content. 

 so we typed in messenger sucks.... cause that was a custom message we had. and it was at HKEY_USERS\.DEFAULT\Software\Yahoo\Pager\profiles\nhyrvana\Custom Msgs    ~we simply deleted the custom msg key from the LEFT pane of the registry and rebooted, and the away message was gone...  ( yours maybe HKEY_CURRENT_USER\Software\Yahoo\Pager\profiles\nhyrvana\Custom Msgs  ~ and do not forget... yours wont say nhyrvana *grin* it will say YOUR user name )

 this give ya at least three ways to remove those status messages and custom aways.

we are sure there are some other ways to edit and remove the customs status messages.. send them in? 

the yahoo help site tells you that you should just make  new ones until the old are gone, because it only holds FIVE. sure, you can do that. simple fast not techy info needed. 

EXPERT ONLY TIP!!!! Roving also sent us this tip ~  WE HAVE NOT USED THIS PROGRAM AND ARE NOT ENDORSING ITS USE>>> IT IS AN EXTREMELY POWERFUL TOOL AND NOT FOR NEWBIE USE!!!  he suggests a program called  xteq .  xteq is kinda like a tweak ui tool.  again.. not for NEWBIES.