exclude one or more portfolio categories from post navigation

I see a previous (#166440) support post attempted to address this same issue but apparently the code has changed and I can’t match up the solution with the code that I find in the “fuctions-enfold.php” file. Also, I’m not clear if the specified categories should be referenced by name or number. I would have commented in the old post if was active. Thanks!

Previous support post isn’t relative any longer or I’m missing something (besides php experience).