Is there a way or command to forcefully change the nick of a user who uses an uneceptable nickname?

Only if you are a server admin or ircop on the network you are connected to. If you are only the owner of a channel or an op then you can not do this.

Thank you for the reply and the link. Awesome useful scripts. I am an ircop and searched for the right command but could not find it. Could you direct me please or post the command to use.

Thanks again

Sorry I've never dealt with ircop commands so I can't help you there. I'd think there would be a help file or commands list for whatever services you are using.

Do the ircd you using suport it? Look online for the information about commands for your ircd, i think unreal have a script you can add to the source.

Try

Allows an Oper to force a user to change their nickname.