I don't think its possible to have no primary attribute, but I'm pretty sure the only thing primary attribute affects is damage so you can go to Gameplay Constants and change it so that the damage doesn't increase as the attribute's points increase.
"Hero Attribute- Attack Bonus per primary att. bonus" is what its called. Set it to 0 and the primary att. won't affect damage.
If you want to make it so it doesn't say "-Primary Attribute" as a tooltip, go to "Game Interface" and scroll down to "Text-General-'Primary Attribute'" and change its value to nothing. I'm pretty sure that will make it so you can't see the Primary Attribute at all. Might leave a "-" though >.>
I do know this - xenforo dropped the ball by not keeping the vbulletin reputation comments as a feature. The loss of the Reputation comments data when we switched to Xenforo really was the death knell for the site when it came to all the users that left. I know I missed it so much and I got way less interested in the site when that feature was gone and I run the site.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory