disable name change

src/components/UserNameForm.js

@@ -144,7 +144,7 @@ class EmailForm extends React.Component {
           <Form onSubmit={this.onSubmit}>
             <FormItem {...usernameProps.fromItem}>
               {getFieldDecorator('username', { ...usernameProps.decorator })(
-                <Input {...usernameProps.input}/>,
+                <Input {...usernameProps.input} disabled/>,
               )}
               {
                 <div className="alert alert-warning" role="alert">{temporaryPromptText}</div>