Please help us with this one instance.
We are happy to provide any sort of evidences/proofs moderators need here.
You don't seem to understand how this works.
Users are free to post what they like, within
the forum rules. So, if you believe the user has violated one of the forum rules, you can use the "Report to moderator" link on the post, explain which rule you believe they have broken and why... If the moderators agree, the post will be removed. If not, it'll stay and there is nothing you can do about it.
Note, if the user is constantly saying "scam" without any evidence to back that up, I would report that as "trolling".
If you are unsatisfied with the work of the moderators, then as pointed out by QuickSeller, you should create a self-moderated thread so you can delete posts as you deem appropriate. Bearing in mind that this could open you up to claims of censorship and preventing open debate regarding your project, should you just simply delete any post that is vaguely critical of your project.