Can I safely uninstall Flash and Facebook apps?
@roxan is incorrect, it is NOT safe to remove stock ROM apps.  If you do so, any future updates from your carrier/manufacturer will not install.

A much safer method is to use an app like Titanium Backup to 'freeze' the apps, preventing them from being seen by the system and running/being updated.  If you really feel the need to uninstall them, you can use Titanium Backup to back them up first (requires root).  That way you can restore them from backup in the future if you need to apply a ROM update.