Remove stored feed data.
Aggregator calls this hook if either a feed is deleted or a user clicks on "remove items".
If your module stores feed items for example on hook_aggregator_process() it is recommended to implement this hook and to remove data related to $feed when called.
$feed: The $feed object whose items are being removed.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_aggregator_remove($feed) {
mymodule_remove_items($feed->fid);
}