Welcome to the shopify community, kindly share the store URL so I can have a look
and potentially provide you a solution
Using the Debut theme, I can't find any option to kill off the CAPTCHA for the stock Newsletter signup form found in the footer section.
The Preferences page ends with the Password protection section. There is no CAPTCHA setting area.
There is a horrible problem with the placement of the reCAPTCHA form on iPhones. If the CAPTCHA is triggered, the iPhone screen doesn't move up to the CAPTCHA form, and just shows the email blank again. The CAPTCHA form is there, just above the visible part of the screen. Our test users are reporting extreme frustration trying to sign up.
Here is a screen shot of the form taken after the CAPTCHA form was triggered. There is NOTHING to alert the user they need to complete the challenge!
I'd rather not try to kill the CAPTCHA since we do get a lot of spam signups on our web site, and really want to find a solution to the placement issue...
Any help would be most appreciated since Shopify's support said all they could do is request the developers look at it for their next update.