Hi there,
first off we do not recommend this ๐ And you must not reset your site or you will lose your existing post content.
But i would suggest the following:
1. Create a staging server of your site so you can make the change safely – If thats not an option with your hosting provider then at least make a backup. And disable any Caches.
2. In Customizer > Additional CSS delete the CSS that was added by the Wordsmith site.
3. Then perform the Import process of Marketer – but on step 2 import demo content you can skip this step so it doesn’t add the Posts/Images marketer will import.
4. You will need to update Logos and Navigation menus
5. Now there will be several Pages and Elements ( found in Appearance > Elements ) that Wordsmith imported that may need deleting or updating as there styles may not work for you in marketer.
Make sure you clear any caches if the layout looks broken on the frontend.