Updated link is here I believe: https://community.aras.com/b/english/posts/hide-relationship-tabs-on-aras-forms
As Angelalp says, this example hides relationships based on the creator, but making use of the Classification instead should be relatively straightforward.
Thanks for this. I ended up figuring it out. I was trying to hide the tabs by default and show them when the classification is selected but it was infinitely easier to just hide the unwanted tabs on selection of classification.
Glad to hear you got something working! If you wanted, I suspect you could hide the tabs in an on-load.