When you are in Edit mode of the profile with the improper 'relationships', you can look on the right side of the profile. Parents, siblings, spouses and children will have an option to 'replace / remove'. Once that is selected, either select the 'remove' link at the top next to 'add/replace' or scroll to the bottom of the page and you will see 'Remove' with the person and relationship. Selecting that will remove that relationship.