How to make wordpress folder (/wordpress) redirect to /?

by

Wait, scratch my comment above. :/

  1. Go to Admin -> Settings -> General
  2. Ensure WordPress URL remains the same (e.g. example.com/wordpress)
  3. Change Site URL to remove the subdirectory (e.g. example.com)
  4. For good measure, go to Admin -> Settings -> Permalinks to flush your rewrite rules

That should be all you need.