How can I de-brand my phone? (install vanilla Android?) I bought a cheap handset (XTE San Francisco, 2.1) from the Orange provider.

I'm not a regular Orange customer so I had it unlocked so I could use my existing SIM.

Orange seem to pre-load their devices with a bunch of useless stuff. Which is now even more useless since I can't access any of them.

Is there anyway I can remove these? I would prefer not to "root" my device if possible.

What about installing the vanilla version of Android, such as the flavour which the SDK emulator has?
You have two options I know of to 'de-Orange' the San Francisco. You can use something like Titanium Backup (requires root) to remove the Orange apps, or install a custom ROM.  

On my San Francisco I rooted the phone (see first part of this video, full details and file downloads here, or alternatively you could use Super One Click) and then used Titanium Backup to uninstall the Orange apps (list in this thread). If in doubt, TB lets you 'freeze' apps so you can make sure everything still works before uninstalling fully.  

Alternatively, you can install a custom ROM (see full video) which I haven't done yet (waiting to see if FroYo ROM becomes available).