Removing pre-installed apps

I've spent a whole afternoon searching here and elsewhere to find out how to un-install apps from my Desire. So far I've had no success follwing the instructions that I've found.

I love my Desire but I have absolutely no use for Facebook, Bebo, Flikr, Twitter and probably a few more. Also there is some stuff from my mobile network (Three) that I don't want.

First I tried uninstalling via Settings>Applications>Manage Applications, but the uninstall button is greyed out for every app on the phone except for one which I downloaded from the Market.

So then I went through the process of rooting the phone via unrevoked. That all went well so now I have the Superuser Permission icon in my list of apps. But still I can't uninstall the apps.

Then I installed Titanium Backup (the free version) and tried to uninstall Facebook. The program popped up a little window to say it was uninstalling the app, then the phone rebooted but Facebook is still there!

How do I get rid of it??

Doesn't always work on pre-installed apps.  With a debranded phone you wouldn't have those carrier-specific apps, but if you really want a bare OS you'll need to root the phone and flash a custom ROM.

Some apps need S-OFF in addition to root. Notable sections are anything that is protected in the /system partition.

Still needs root.

To quote MC Hammer:

You can't touch this partition.