You should fix the relationship rather than trying to delete the profile. Go to her profile, hit the "Edit" tab, then over on the right click on the "add/edit" option where she's listed as a sibling. Scroll all the way down to the bottom of the edit page and you'll find the "Remove Sibling" section.
Once she's removed as a sibling, you can go to the "Edit" tab again and add her spouse. Make sure you have his profile number handy (Boies-27).