Note: This will delete the packet and unlink all of the files uploaded to it. You'll need to reupload the files if you intend to use them elsewhere.
If you want to just delete one of the files you uploaded and not an entire packet, see How to Delete a File from a Packet.
From the Teacher Tools menu on the left, click on My Packets. You can reach a packet any number of ways, but this may be the most direct.
Click on the name of the packet you wish to delete.
In the Actions menu on the right, click Delete Packet.
You will be asked to confirm that you want to delete the packet. Click OK if you are certain.
You'll be redirected to the course page for the course that the packet belonged to. You should see "The packet has been deleted."