Where would i change the command from /claim to /claimboss?

It would have to be changed in the plugins file itself.

How exactly is it possible for you to do it and send me the file?

You can open the plugin in an editor such as Notepad++, find "claim" and "claimboss" and replace them with what you'd like, save the file, and upload to your server.

On top of what Wulf has said.
I would show exactly where to locate it, but I have a half finished reqrite of the file in my project list, which would be of little help.
Just sift around on it and look for a ChatCommand and/or ConsoleCommand in the code, and go ahead and change it to whatever ya want.

I found it thank you.