Users field manually delete from database cache problem
I'm really not sure why you'd want to remove a column from a field table but just looking at your problem as is, a way by which you can disable caching of field values in the cache_field bin is by letting Drupal know that you don't want values for the field instances attached to a given entity type to be cached at all.

You can do this by implementing hook_entity_info_alter() from a custom module and setting the field cache key for the user entity as shown below:

function mymod_entity_info_alter(&amp;$info) {
  $info['user']['field cache'] = FALSE;
}


You might find the documentation of hook_entity_info here useful. You might also want to lookup the definition of field_attach_load() from here.