Developer, FYI, you may wish to check the banner plugin with WP, es_ES language installed, I could not create a banner, all fields were filled in but still kept saying I needed one last field to be entered (sorry forgot which one).
Using CodeStyler, I deleted the Spanish translation and script (plugin) correctly. Translation is still missing a few translations, here and there. Might consider an option to disable WP installed language on backend. Good luck.