2003 Neon code PO441

Hi guys, my 03 Neon SE has had this code (P0441) come up twice before. First time, cleared and didn't come up again for 6 months. Came up again last week, and again this week. I'm going to buy a new gas cap as recommended by my mechanic, and see if it won't come up again, but how can I clear this code myself without a special device. Can I just disconnect the negative battery cable? Will that impact my aftermarket alarm?