mega menu + off canva

Hi. The easiest way is just to use CSS

@media (max-width: 992px) {
    .sp-megamenu-parent {
        display: none;
    }
}

But it seems that your template has been customized and this was not done correctly. Since this should work from the box just as you want.

I suppose that the classes in the HTML code of the template were changed and/or template.css was edited, which is not recommended to do.

Better to deal with this. Otherwise, it can lead to unpredictable consequences.