You may find that an entire branch is in the wrong location in your family tree.
For example, person A and all his descendants may be under person B, when they are really the descendants of person B’s brother.
In this case, use the Remove Connection function to disconnect person A from his parents.
Then use the Connect feature to connect person A as a child to B’s brother.
You can read more about how to use the Connect Remove Connection feature here: How do I use the online Connect Remove Connection feature?