How to delete a family string

I believe this article will will help you to solve the problem:

A person in Family Tree has the wrong spouse

Article Id: 1432, Published November 25, 2020. You can correct an incorrect couple relationship at any time. Here are the steps to remove or replace an incorrect spouse.

Tip: removing or replacing an individual's records can feel intimidating. Rest assured that changes can be undone in the Latest Changes feature. It's also helpful to record the ID number so that the removed or replaced person is easy to find later on.

Steps (website)

1. While signed in to FamilySearch.org, navigate to the Person page of the individual with the incorrect spouse. 
2. If you do not see Vitals near the top of the page, click the Details tab.
3. Scroll to the Family Members section.
4. Under Spouses and Children, you can view the different relationships. 
5. In the box showing the incorrect couple relationship, click the Edit icon .
6. Click Remove or Replace next to the incorrect spouse. 
7. Click the check box on the Remove or Replace screen to verify that you reviewed the relationships, sources, and notes. 
8. Do one of the following:
   1. To remove an incorrect spouse, click Remove Person. Explain why, and then click Remove.
   2. To replace an incorrect spouse, click Replace Person. The Replace Person screen appears.
      • If you know the spouse's ID number, click Find by ID Number, enter the ID number, and then click Find. Click Add Person. Explain your reason for the change, and then click Replace.
      • If you do not know the spouse's ID number, complete the search fields, and then click Next. If the correct person appears in the list, click Add Person. Otherwise, click Create New to create a new record. Explain your reason for the change, and then click Replace.

Good luck in your efforts in working in your family tree.