jQuery ajax to update user

userUpdate.js

jQuery(document).ready(function($) {
   $.ajax( {
      url: Slug_API_Settings.root + 'wp/v2/users/' + Slug_API_Settings.current_user_id,
      method: 'POST',
      beforeSend: function ( xhr ) {
      xhr.setRequestHeader( 'X-WP-Nonce', Slug_API_Settings.nonce );  
      //Slug_API_Settings comes from script I enqueued in theme's functions.php which makes some vals available from PHP to the JS
      },
      data:JSON.stringify( { roles: ["Free"] } )
   } ).done( function ( response ) {
   console.log( response );
   });
});