Can i modify .js directly on traccar Windows?

Good Morning.

I'm trying to modify traccar after installing it on windows, just small things like removing some buttons or changing colors in .css.
But on my first attempt to remove a button it has no effect. (I am restarting the service after to update)

For example in Login.js i changed this code

buttons: [
    /* disable register
    {
        text: Strings.loginRegister,
        handler: 'onRegisterClick',
        reference: 'registerButton'
    }, */
    {
        text: Strings.loginLogin,
        handler: 'onLoginClick'
    }]

See img please: http://oi67.tinypic.com/9isfhz.jpg

I can do it this way or I have to download the source code and recompile?

You have to compile a minified version, or use debug mode.

How to use a Debug mode?
Need add mode="debug" in my file release.hmtl?

Before:

<script id="loadScript" src="load.js"></script>

After:

<script id="loadScript" mode="debug" src="load.js"></script>

I tried but doesnot work.

You can just open debug.html. Have you cleared the cache?

How do I clear the cache?

Cache is in your browser, so you need to check your browser documentation.