John from Goleta,
According to Microsoft, Windows Defender should automatically turn off if a non-Microsoft antivirus or antimalware app is installed and protecting your device. You don't need to uninstall Windows Defender. Did/do you have any other antivirus software or malware protection installed on your PC? We would need to check your account if anything is preventing the security suite from activating. Please email us at cox.help@cox.com so we can authenticate you and get to the bottom of this for you. I recommend including a link to this thread and the details of the trouble you're having, including the steps you took up to the point where you see the error. We'll also need your full name and complete street address in your email. -Colleen