the way you have to do it is very confusing.  I just had this issue the other day.  Here is a link concerning it but even the link can be difficult to follow:

https://accountants.intuit.com/support/en-us/help-article/file-management/adding-removing-partners-s...

Went to K1 screen cleared all data

Went to forms list, found untitled K1 and deleted it. 

Had the exact same issue with an S Corp K-1 last year there were 4 shareholders.  By year-end only 2 as the 2 remaining bought-out the other two.  I was able to eventually fix and e-file.  I don't remember how I did it but now IT"S BACK.

Why is this still an issue!