If you edit your family tree online, please read the following article: How do I delete a person from my online family tree?
To delete a person in your tree in Family Tree Builder, please do the following:
1. Open your tree in Family Tree Builder.
2. Find the person you would like to delete and open his/her personal card.
3. Click on ‘Edit’ button and select ‘Person’.
4. Click on ‘Delete Person’.
5. You will receive a confirmation message if you wish to delete this person`s card. Click ‘Yes’.
Please note: if you have children attached to the person you are trying to delete, you may receive a notification that the person cannot be deleted. In this case you need to detach these person's children, and then delete the person. For more details please read here: How can I attach and detach children in Family Tree Builder?