You can’t do that directly inside the CF7 plugin you need to modify the CSS.
Add the following to your theme’s style.css file:
.wpcf7-recaptcha > div {
margin: 0 0 15px auto;
}
PLEASE BE NOTED:
If you add the above code, it will take effect to all your recaptcha fields in every forms on your website.
Often times, we would like to only do this to a certain form, this is how you can do it:
First: Add an ID to the recaptcha in Contact Form 7
[recaptcha id:enquiryFormRecaptcha]
Second: Customize your CSS
#enquiryFormRecaptcha > div {
margin: 0 auto 0 auto;
}
Good luck!