You can stop Yahoo! SpamGuard from automatically sending suspected spam messages to your Bulk folder if you want. It’s hard for us to imagine why you would want to do this, but you’re the boss. So here’s how you do it:

1. Click Options in the upper-right corner of your Mail page.
2. Under “Management”, click General Preferences.
3. Find “Folders/Search Results”. In the part that says “Special Folders”, un-check the box next to "Redirect incoming unsolicited mail to the Bulk folder". That is, remove the check from the box.
4. Don't forget to click Save before you leave the page.

Now any spam you receive will be delivered to your Inbox, and no new messages will go into your Bulk folder. If you want to start using the Bulk folder again, it’s easy to turn it on by placing a check back in the “Redirect incoming unsolicited mail...” box.

The Bulk folder is a permanent folder in your account, and these types of folders can't be removed or renamed. Your Inbox, Sent, Drafts, and Trash folders are also permanent.