PLEASE NOTE: Alfred is currently in beta and as such, these help pages are currently being developed.
We'll be very sad to see you go, but if you really must uninstall it, you can simply delete the application from your Applications folder.
For a cleaner uninstall, uncheck "Launch Alfred at Login" in the General preferences tab or go to your System Preferences > Accounts > Login Items, select "Alfred" and press the minus button to remove it.