I think you're not website admin or you're not in forum Admin usergroup. Navigate to Users > Your Profile admin page and make sure your Forum Usergroup is admin:

I cannot find the page like yours from my dashboard. Here is my user page.

I see it on your screenshot:

Dashboard > Users > Your Profile

Posted by: Robert

Please read User Delete doc, you can delete user with all content of this user. Make sure you use the latest 1.2.0 wpForo version. We don't support old version.

https://wpforo.com/docs/root/members/member-manager/

Hi,

I am on v 1.4.1 and still  not able to delete members.

Deleted it from the WP Users, it does not show up in there any more.

However it still shows up under Forums -> Members. Clicking 'delete' on any member there only lands me to a page saying "User deletion is not allowed from this screen."

Cleared User cache, logged him out from everywhere through the admin panels, retried registering same user name same address. I am getting error on both address already in use and username taken.

Help please

Please open phpMyAdmin database manager of your hosting cPanel, find the _wpforo_profiles table, search this user and delete the row. As far as I see something wrong with this user data. wpForo doesn't have such problem, this is a user specific issue, or website specific issue. You can install a fresh Wordpress and test it with wpForo. It doesn't have any problem with user deleting function.