Hello, @DCD,
Sorry for the inconvenience but in order to solve your issue First go to XStore >> Theme Settings >> Woocommerce (Shop) >> Single Product Builder >> and Delete the Sizing guide element from the section. See the Screenshot for better reference: https://postimg.cc/LqVbQGwk
After that You can activate the size guide only for certain products from Dashboard >> Products >> edit a product > [8theme] Product Options > Single layout > Size guide image. See Screen Shot for better reference: https://postimg.cc/18h5cNpx
Further, you can read our theme documentation article here: https://xstore.helpscoutdocs.com/article/140-xstore-size-guide-on-product-page
Regards 8Themes Team.