How to remove X-Frame options in DIVI theme?

I'm building a simple plugin for Divi that needs to display a page of my website in the plugin's admin page.
When I tested the plugin I used the elegantthemes.com website as a sample in an iframe but then when I went to replace it with my own Divi based website I get this error

Refused to display 'url' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'.

I understand that the X-Frame options are denying permissions to embed my site but I cannot for the life of me figure out where in the DIVI theme the options are set. I need to remove it completely since ALLOW_FROM won't work, it needs to be defaulted to allow all domains.

I don't want to modify the WP core files, there must be some way in the theme files right?
Any help will be greatly appreciated.

 

Hi Admin thanks for the advice.

I'm not sure I'm skilled enough to work in .htaccess, my coding knowledge is very limited (I'm a designer), I get around by doing a ton of research and I understand most of what I read in the core files but I can't necessarily put it into practice by myself.

This is what the file contains:

# BEGIN WordPress
# The directives (lines) between `BEGIN WordPress` and `END WordPress` are
# dynamically generated, and should only be modified via WordPress filters.
# Any changes to the directives between these markers will be overwritten.
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress


After combing through the WordPress core code I found where the X-Frame-Options are set in ./wp-includes/function.php

I commented out the function and also commented out the function but still got the same error in the page trying to load the iframe. I then also commented out the 2 lines that add it in default_filters.php ie. ('admin_init', send_frame_options_header) and ('login_init', send_frame_options_header) and it still doesn't work.

I then tried to instead remove the actions by adding the following to the functions.php files
remove_action( 'admin_init', 'send_frame_options_header', 10, 0 );
remove_action( 'login_init', 'send_frame_options_header', 10, 0 );

...which also did nothing.

Could you tell when what to add or remove from the .htaccess file as a last resort please?

 

Thank you, adding - Header always unset X-Frame-Options - in .htaccess removed the error but it's now throwing a 403 access forbidden error instead. I'll research further. Thanks for you help so far.

Error:
Failed to load resource: the server responded with a status of 403 ()