Remove custom fields from WordPress database using SQL

Step 1
Login to your hosting account and launch myPHPadmin from the cPanel, or equivalent, to access the WordPress database engine.

Step 2
Enter a select SQL command to list all the meta keys you want to remove. In this example, I want to find and eventually remove the meta key dcssb_short_url.

SELECT * FROM 'wp_postmeta' where 'meta_key' = 'dcssb_short_url'
Step 3
Once you are satisfied you’ve narrowed down the selection, issue a delete SQL command to remove the rogue data

DELETE * FROM 'wp-postmeta' WHERE 'meta_key' = 'dcssb_short_url'
Step 4
Issue the same select SQL command again, to verify all the offending records have been deleted.

SELECT * FROM 'wp_postmeta' where 'meta_key' = 'dcssb_short_url'
If you get no results returned, it means that you successfully deleted the records.