How to remove email marketing notification after checkout?

I want to remove the notification of successful registration at checkout when a customer register to newsletter.

Hello, tolis88gr!

Please copy your request on sales@cart-power.com and we will help.

Best regards,
Cart-Power

It looks like notification from 3rd party module. Try to contact addon developer

Its from email marketing addon of cs-cart.
email

I have just checked language variables (popup title and content) and failed to find such values on the clean installation