If you can use the custom SQL option you can do this at that point. The other option we use is to create Views in our MS SQL database where we are selective about what fields to include. Where is your data coming from? What version of Tableau are you using?
I am using version 8.2 and am connecting to Microsoft SQL Server.
Anna that's exactly our setup. So your best bet is to write some code in SQL Studio that creates views with the fields you want, and then connect to that view. You'll need to get the permissions to CREATE VIEW, which the admin can give you. Let me know if you need any help with the code.
I use the same setup of Microsoft SQL server and also wanted to remove columns of data before it reached Tableau so I could limit the data coming through and speed up processing time. It's quite easy in 8.2 now in my opinion.
First connect to your data and throw in your tables, and link them accordingly (IF you're linking tables...im NOT in the screenshot below).
Then, go to Data -> Convert to Custom SQL
Lastly, go through and delete the columns of data that you don't need.
Just highlight and delete like in Wordpad. Pretty easy.