I'm new to Meta Box. This is a N00B question. I did a search, but either used the wrong search term or misunderstood the result.
I created a custom field in the : ee_custom_field in the Custom Fields UI area. I ended-up not needing it, so I deleted it. However, when inserting data via a shortcode (using Oxygen), I can see that the field still exists.
My question is; how can I delete the not-needed field from the WP database?
WordPress does not support an option to delete the custom field value aka post meta (key and value). You can use this plugin to delete the custom field in the database https://wordpress.org/plugins/bulk-delete/.