With that light, I'd suggest doing a moss carpet. Marsilea minuta might work, but you may need to add a second bulb.
If you are trying to keep fish in that tank, I don't think removing your filter altogether is a viable option. You could look into one of the mini canister filters, and I think there is a good DIY to make a small, cheap one ($30 or less) on either this site or APC. If you're going to have a fish that's not a beta, you need filtration.
edit:
This is the filter I was talking about.