[Plugin: Genesis Subpages as Secondary Menu] Don't show dropdown

Hi there,
thank you for this plugin. I am wondering if there’s a way (filter?) to prevent the dropdown menus from being shown in the subpages menu.
I am working on a site having a 3 levels menu structure, and by default the 3rd level is shown as a dropdown submenu of the subpages menu. However the client does not want a dropdown menu in the site, so the 3rd level will be shown elsewhere (sidebar), but how can I hide the dropdown from the subnav?
Right now I have hidden it with CSS, but I would prefer to exclude it at PHP level.
I have seen the documentation about the filter for excluding subpages by ID, but in this case I don’t think it can be a good solution (I should list all the pages that are at 3rd+ level, not very handy).
In Genesis settings I disabled the dropdown on the secondary menu, but it doesn’t make any difference (I think that option only controls wether to use pure css or superfish).
Thank you.

https://www.ads-software.com/extend/plugins/genesis-subpages-as-secondary-menu/