How to force delete a wiki?

I’ve run into some weird problems where some projects have wikis and some don’t.

Som think they have wiki’s and really they don’t.

When I try to backup I get the following error:

sudo gitlab-rake gitlab:backup:create
Dumping database ... 
Dumping PostgreSQL database gitlabhq_production ... [DONE]
done
Dumping repositories ...
 * one/dcss ... [DONE]
 * one/dcss.wiki ...  [SKIPPED]
 * dev/sample-server ... [DONE]
 * dev/sample-server.wiki ...  [FAILED]
failed: /opt/gitlab/embedded/bin/git --git-dir=/code/gitlab/git-data/repositories/dev/sample-server.wiki.git bundle create /var/opt/gitlab/backups/repositories/dev/sample-server.wiki.bundle --all
fatal: Need a repository to create a bundle.
Backup failed

I can’t find or delete this special wiki project from the web GUI.

I’m attempting to delete it from the rails console, but I could use some help on the syntax. Something along the lines of:

Project.unscoped.where(repository_storage: 'default', name: 'sample-server.wiki').find_each do |project|
  puts "Found project #{project.name} "
end

but his returns nil.

please help.

Thanks.

SOLVED
Just followed this advice to stop server, manually delete repo folder of disk and restart.