[i"My question is, can I just uninstall it from my Device Manager??"

No. You'll need to disable the integrated sound in the BIOS. It's easy enough; you just press the delete key on boot (at the POST stage, or before Windows starts loading), and then you look for an option called integrated periphrals. Before you do this, you'll want to uninstall the integrated audio drivers in add/remove programs, run driver cleaner, then turn off the PC and install the Audigy. After disabling the onboard sound, boot into Windows and install the Creative drivers.