Remove WordPress Logo

Found in read-me.txt about logo but not edit the button color/appearance?

Cheers

in the plugin folder there’s a /theme/ folder. Inside that there’s a file ‘password-protected-login.php’ that you can customize. Upload it to your site’s theme folder and the plugin will default to your custom one.
In there you can put whatever css or template changes to the login screen.

If you replace the WordPress logo image (wordpress-logo.svg) in the /wordpress/wp-admin/images folder, you can display any image or logo you want in the Password Protected page. You will need to adjust the background-size setting as well as the margin, height & width settings.

Next open the password-protected-login.php file located in /wordpress/wp-content/plugins/password-protected/theme and add your adjustments to the section

<style type="text/css" media="screen">
#login_error, .login .message, #loginform { margin-bottom: 20px; }
	.login h1 a { background-size: 700px auto!important; height: 100px!important; width: 700px!important; margin: 0px -200px 25px;!important;}
</style>

Other adjustments include:

.login h1 a {
    background-image: none, url("../images/wordpress-logo.svg?ver=20131107");
    background-size: 700px auto;
    background-position: center top;
    background-repeat: no-repeat;
    height: 100px;
    font-size: 20px;
    line-height: 1.3em;
    margin: 0px -200px 25px;
    padding: 0px;
    width: 700px;
    text-indent: -9999px;
    outline: 0px none;
    display: block;
}

The plugin will also look for a stylesheet in your theme folder called “password-protected-login.css”. You can create this stylesheet (if it does’t exist) and use that to style your login page.

See here if you want to add a stylesheet in another location.