Hey there aguy10, thanks for reaching out. We see you are inquiring about how to enable developer mode and how to disable Oculus Guardian.
To answer your questions, yes, you need to have a credit card or a cellphone number to access developer mode, and accordingly, sideloading.
For Oculus Guardian to be turned off, you will need to enable Oculus Developer Mode. Settings > See All > Developer and there should be a switch to disable guardian.
To enable Developer mode on your device,