First, install Child Theme from the Theme bundle. Open functions.php file with WordPress Editor or AceIDE and Change speaker/schedule URL slug file on exhibz-child\functions.php folder and write the below code

//For speaker slug

add_filter( 'register_post_type_args', 'exhibz_speaker_slug_register_post_type_args', 10, 2 );
function exhibz_speaker_slug_register_post_type_args( $args, $post_type ) {

   if ( 'ts-speaker' === $post_type ) {
      $args['rewrite']['slug'] = 'speaker'; //rename solutions
   }

   return $args;
}

//For Schedule slug

add_filter( 'register_post_type_args', 'exhibz_schedule_slug_register_post_type_args', 10, 2 );
function exhibz_schedule_slug_register_post_type_args( $args, $post_type ) {

   if ( 'ts-schedule' === $post_type ) {
      $args['rewrite']['slug'] = 'schedule'; //rename my-service
   }

    return $args;
}