This is a touchy subject. As a world tree anyone can come along and change your entries. The community ranges from professional genealogists to 12-year-olds and I wouldn't be surprised if some are younger - I started researching at age 10. So we don't want to discourage them from getting better, but we do want to preserve our work.
So first, check the sources. Maybe you'll be pleasantly surprised and these are people you didn't know about. Next on the right hand side check Latest Changes to figure out where these people came from - is it a bad merge that needs to be undone? If it is a bad source, I'd disconnect the person and reconnect them to the right family if I can. If there is no source and I'm sure they don't belong to the family, I'd disconnect them and in the reason field I'd explain why they don't belong. You can also send a message to the contributor and nicely explain what you've done but as mother always said, "If you can't say something nice, don't say anything at all." Sometimes I get pretty frustrated and I have to wait awhile so I don't say something mean.
Finally, to answer your question.
To detach the person as a husband, bring up the wife's page, click on the edit icon in the marriage box, click on Remove or Replace and follow the directions to remove the husband. Do the opposite if you are removing the wife.
If the person was added as a child, click on the edit icon next the their name where they are listed as a child. Click on Remove or Replace next to the child's name and you can remove both parents. If you only want to remove one parent, click on the Remove or Replace next the to the parent's name.
Then I check the sources and disconnect any that don't belong to my person and then I make sure the source is still connected to the person I removed so it doesn't get lost.
If you go to the person who does not belong, you will see a box with a pencil in it next to their name. Click on that box and you will be able to delete the person from there.
For starters ...
Most new (and, some old) Users/Patrons DO NOT understand the basic nature and premise of "Family Tree" of 'FamilySearch', when they join in.
Please let me explain ...
We do not have our OWN "Tree" in "Family Tree" of 'FamilySearch'.
We ONLY have "Branches" (ie. Ancestral" lines), that are interconnected, in this SINGLE "One" World "Tree", for all of us, that is "Family Tree" of 'FamilySearch'.
"Family Tree" of 'FamilySearch' is NOT like 'On-Line' "Websites" (eg. "Ancestry_com"; or "MyHeritage_com"; or, the like); and/or, 'standalone' personal (computer) programmes (eg, the OLD, now no longer supported, "PAF"; or, "Ancestral Quest"; or, the like).
We DO NOT have "Private"/"Personal" 'Trees' in "Family Tree" of 'FamilySearch' like other 'On-Line' "Websites"; and/or, 'standalone' personal (computer) programmes.
We do not even, own; or, manage; and, are NOT even responsible for, the "Deceased" individuals/persons in "Family Tree" of 'FamilySearch'.
And, in fact, we do not even, own; or, manage; and, are NOT even responsible for, our OWN "Deceased" Ancestors in "Family Tree" of 'FamilySearch'.
We can certainly "Watch"/"Follow" them in "Family Tree" of 'FamilySearch'; and, address/fix any 'wayward' alterations; but, that is it.
"Family Tree" of 'FamilySearch' is built on a "Open Edit" Platform - hence, why any registered User/Patron can "Edit" (ie. Add, Delete; and/or, Change) ANY "Deceased" individual/person in "Family Tree" of 'FamilySearch'.
Just something to consider.
I am sure you have ...
That said ...
Just in case ...
BEFORE going about "Removing" anyone for one's "Ancestral" lines in "Family Tree" of 'FamilySearch' one must to their due diligence ...
One may be wrong ...
None of us are perfect ...
We all make mistakes ...
IF, one has done their due diligence and is 100% certain that an individual/person (or, even, couple) is (are) NOT part of one's "Ancestral" lines; THEN, one can "Remove" them from one's "Ancestral" lines.
Here are some "Knowledge Articles" in 'FamilySearch':
A person in Family Tree has the wrong spouse
How do I correct parent-child relationships in Family Tree?
I hope these help.