Hi Shahed,
Thank you for reaching out and thanks for using BoldGrid Post and Page Builder for WordPress!
You may be able to use a plugin like Code Snippets or your functions.php file to de-queue the offending stylesheets. You can use the wp_dequeue_style function that’s hooked into the wp_enqueue_scripts hook.
Here’s an example on how to dequeue a style that you might find helpful, make sure you’re using a priority higher than 10 when you add your action.
I hope this helps. Please reach back out if you have any other questions.