You need to go into a spouse or parent. Click on their profile, go into the edit - if they are a child go to the add/edit (within edit mode) and it comes up with a new page to add.
Scroll to the bottom of the page - this gives you the opportunity to 'remove' the person - click on remove and save.
Come back to the forum if you need further help.
Remember when you do unlink them if there are spouses, children the other parent - check them.