IRC servers use the reply from a ident request to display before the @ symbol. If they do not get a reply, the will use what is provided in the "username" setting with a ~ prefixed to the string.
To remove the ~, the IRC server needs to get a ident reply, which is returned by the idetnd deamon.
Once you install the identd deamon, it will reply with your username (the username you sign in with to your shell). This can't be changed, as standards state that this is what should be replied.
If this is a shell server that you have no control over, you should contact the admin, and ask if he could install it. If he says it is installed, it is most likely that the shell is unable to reply on time, and the ident connection timesout.
you jsut want it to say what you want, ~ isn't really an issue? well then...
just set the correct value in the config. as i gather from ppslim's post, you DON'T have identd installed and that really shouldn't be a problem. unless the ~ really really bothers you, in which case install identd and make sure your account name on the shell is serv-r or whatever you want it to say there...