Did you know there's "Convert to Custom SQL" menu under Data?
See the video here: https://kb.tableau.com/articles/howto/editing-custom-sql
After you get the Custom SQL text - just remove the line with field you do not want. And do not forget to adjust the commas as needed.
p.s. why do you want/need that? You can just hide column in Tableau if you do not want to make it visible.