I’ve noticed that several people in my tree suddenly have “Unknown Spouse” lines on their detail page. I have one on my own page but have only been married once – to the same girl for the last 55 years - her mother won’t take her back - so I’m stuck LOL – Anyway, I can’t find a reason for this line to be showing up – there is no information relating to an “Unknown Spouse” – and the " Spouse:" window - on the right - has no information at all – Note, Sources, Media, Task and Address are all empty – Mother and Father are vacant - yet I can’t delete this non-existent spouse line – because the message being returned - when I attempt to do so states “You can only delete a fact” - but there is no fact to delete as I have only been married one time and she’ s listed as a current spouse. Domestic tranquility would be in jeopardy if she thought we had a secret wife to deal with somewhere LOL Any ideas on how to remove this unwanted line in the “Person” detail sheet ?
Check first to see if a child was linked incorrectly, i.e. just to you and not your spouse. If that looks good run the database tools, particularly “Clean Phantom records” to see if that eliminates that secret admirer.
Thanks for the valuable response – this is only my second day with the new RM8 – I’m migrating over from Family Tree Maker 2019 – primarily because I like the way RM 8 allows me to edit “places” and also conducts the “Family Search” hint exploration so much faster 
I’ll probably ask a number of stupid questions - sorry LOL
Happy I could help; no such thing as a stupid question unless it’s an unasked one.
So far none of the suggestions posted here have worked for me.
@greenshrink-- I’ve had unknown spouses off and on for no apparent reason-- so what I did was UNLINK the named spouse from the family leaving just one parent and the kids-- then go to the unknown spouse-- then go to add spouse and pick SELECT EXISTING PERSON–once you click on the name of the spouse from your list, it SHOULD ask if you want to attach them to the current family or create a new family-- it’s the only way I’ve been able to get rid of an unknown spouse sometimes
on unknown persons NOT connected to anyone, I just name them-- Jane Doe ETC then hit delete–that MIGHT work for an unknown spouse
I will try that, thank you.