BleepingComputer.com: How 2 Remove Endpoint Firewall AFTER Endpoint Has Been Wiped?

I'm using an old work computer I got without having to wipe the drive. I don't work there anymore, so my SEP hasn't been updating since May.

Things seemed fine, but I've been having a ton of problems with Google Redirect Trojans (another post in another forum...sigh), so I figured the outdated firewall/antivirus defs needed to go So I uninstalled SEP..TWICE, actually; first using a Symantec instruction doc on how to do it via erasing Registry entries. But I noticed the firewall was still active, so I dug deeper & actually got ahold of the current Norton CleanWipe, and that seemed to really get rid of EVERYTHING relating to Endpoint, including Live Update (which I imagine the firewall would need to stay current).

I then loaded Avast...it's working great...but I noticed it doesn't have a firewall. I have Iolo System Mechanic Pro, and during a scan it said that it detected that Endpoint Firewall was active & 'protecting' me. But when I try to remove it via Add/Remove Programs (I tried "Modify" and "Remove"), the removal process seems to work, but then it rolls-back the process & says there was a fatal error in the installation (removal, actually). I'm pretty sure it must be the fact that a company/Symantec firewall policy was installed, as it says that when you check "Windows Firewall" in Control Panel.

So now I have antivirus, but what I believe is a hobbled, non-updating firewall (if it works at all). Is there any way to get rid of the firewall & activate Windows Firewall if I can't change the 'policy'? Maybe via futzing w/the registry? I've killed/removed pretty much everything Symantec-related in my Registry, but of course there are so many 'levels', maybe the firewall settings are hiding somewhere.

Thanks for any help/insight you can afford me!