How can I disable the default theme picture lightbox

My website: https://nomansland-urbex.com/ Hello there, I wanted the pictures of my different articles on my website to be openable in a lightbox with arrows so the visitors could navigate easily and quickly among them. The default theme layout only allows me to open one at the time, that's why I installed a plugin called "Easy Fancy Box", that created the results I wanted so I'm really satisfied ! The problem is that now I want to delete the default theme lightbox, only to let the one of Easy Fancy Box and not the two as now. Here's an example (click on any picture): https://nomansland-urbex.com/reve-denfant How can I do this ? I'm using wordpress.org directly online. Thank you very much for your help, this is the last thing I want to fix before releasing my website ! Regards, Quentin