No, that's not how it works.
Because it's a rooted device you can't remove stuff with no consequences. If we were talking about a phone you could remove stuff and then add it back with no problem. You would just go through the reconfiguration process again. Here it's not possible because we are tricking the device to do something it normally wouldn't do.
Everything works because there's a resident Google Account on the device (that's the purpose of doing the YouTube thing). Android revolves around this account unfortunately (speaking from a Windows Mobile perspective mind you). You have to play along with it.
You can't uninstall Gmail. I thought you just wanted to remove an account? An account that was added after you rooted. If you corrupt the Google Account on the device you'll have to reroot or re-enable Market manually which in turn restores everything.
Here's what you need to do to enable Market manually:
http://www.nookdevs.com/NookColor:Manual_market_enable
If you don't want to do the above, you'll need to re-root.