Cannot delete records in a file field.

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In my case I want delete the file from a file field (works - no records in file_managed), but it does not delete the data from the tables (field_data_field.../field_revision_field...).

When I use the action to set nothing, then it creates a new entry in file_managed.

I was able to do with with the custom php code. Here is a snippit. I got this code from http://dropbucket.org/node/235 and modified it. In this example my rule generates a list of nodes and loops through them. If you don't have a loop you may need to change [list-item:nid] to another token.

// Load the node.
$node = node_load('[list-item:nid]');
// Get the language for the file field.
$lang = field_language('node', $node, 'field_my_file_field');
// load the file
$file = file_load($node->field_my_file_field[$lang][0]['fid']);
// unset the field for the node
unset($node->field_my_file_field[$lang][0]);
// delete file from disk and from database
file_delete($file);
// Save the node.
node_save($node);

I don't see any bug here, and no further information was given.

Deleting a reference to a file does not delete a file, that's the expected behavior. If you want to delete the file, #6 seems like a good solution.