I have a VPS which does not has any Cpanel installed. I can connect to the server via FileZilla and Putty via Root Access. I also have another username "webmaster" and a password which I use to give to other developers if I give them some task on freelance, elance etc

I want to change the password for "webmaster". How can I do it?

If I connect via FileZilla, using login details of "webmaster", I get connected. But when I use same details in Putty to connect to the server, I get a message, Access Denied: Wrong ID or Password.

I can only log in to the server using root access. I do not know how to change the password for other user. or delete the user and create a new user with a new password. I do not want to delete or change the root password.

looking forword from responses with solutions