Profiles cannot be deleted; they can only be merged or attached elsewhere. So what you would do is unhook them from the wrong relatives by going to the Edit tab, then look on the right side and click on "Edit Mother", "Edit Father", "Add/Edit Siblings", or "Add/Edit Spouse"... whichever is necessary. Then scroll all the way to the bottom and you'll see the place where you can remove the mother, father, siblings, etc.
To add the right relatives, go back to the Edit screen and "Edit Mother", "Edit Father", etc... then at the top, you'll see a place to add that person. If the relative already has a WikiTree profile, put the address in the window; otherwise, you can add a new profile for that person.
Hope this helps!