How to Remove the wordpress header

Yes, you can disable the ‘admin bar’ (Toolbar – Checkbox at each user) per user.

that’s great just done it thanks .. but people can still check it by entering to their profile.. Is there any way how to disable their profile viewing as well ?

You can redirect them to the homepage with this added to functions.php of current theme:

function soi_login_redirect( $redirect_to, $request, $user  ) {
	return ( is_array( $user->roles ) && in_array( 'administrator', $user->roles ) ) ? admin_url() : site_url();
} // end soi_login_redirect
add_filter( 'login_redirect', 'soi_login_redirect', 10, 3 );

May not work (as is) if theme has included it’s own login actions/hooks.

Source:
https://tommcfarlin.com/redirect-non-admin/

Note: Above should be done in a Child Theme or this edit will be lost on theme update.

I would look into a plugin solution.

I found this article very helpful: https://wplift.com/controlling-your-clients-wordpress-experience

Best of luck!