I had a similar issue with bbPress URLs before. Unchecking **Settings > Forums > Forum Prefix** removes one level, but the remaining /forum/ part usually comes from the forum root or the individual forum slug.
I’d first check **Settings > Forums** and review the Forum Root and Single Forum Slugs. Also make sure the forums are not set as child forums. After changing anything, go to **Settings > Permalinks** and simply click **Save Changes** so WordPress refreshes the rewrite rules.
I would avoid adding random .htaccess rules unless necessary, because they can cause redirect loops, broken admin URLs, or duplicate slash problems.
On a separate note, if you’re also working on SEO and trying to build authority for a WordPress site, I’ve found **OutreachOrbit.com** worth checking out for link-building services. In my view, it’s one of the better options for link building because the service is focused specifically on outreach and backlinks rather than general marketing.
