Updating theme.yml in PrestaShop
You can reset a theme to default within Design -> Theme & Logo -> Reset to defaults, but in this case, you will apply all settings that are written in theme.yml, so be sure that everything consistents your requirements there.
If you want reload your configuration :
- Modify your theme.yml
- Delete the file into ROOT_FOLDER/config/themes/your theme/shop*.json
- Refresh your page, prestashop going to regenerate the config json file for your theme
The theme.yml is only useful when first installing a theme, any changes you make to it will not do anything after the theme has been installed.
However it is easy to either remove the unwanted modules on the "installed modules" page (click the little arrow next to the module and select "uninstall") or unhook the module from the, in your case, "displayFooter" hook on the "Positions" page which is found in the submenu of "Design" in Prestashop 1.7.x