How to disable a root CA (Certificate Authority) certificate on Mac computer? I don't know this root CA and don't want to trust any Websites that uses certificates signed by this root CA.

On Mac computers, you can not delete a root CA certificate using Keychain Access as the certificate manager. But you can disable it by turning on the "Never Trust" flag as shown in this tutorial.

1. Open "Launchpad > Other > Keychain Access" on your Mac computer. You see "Keychain Access" window.

2. Click "System Roots" in the "Keychains" list on left. And select "Certificates" in the "Category" list. You see a list of trusted root CA certificates.

3. Scroll down in the list and double-click on "GeoTrust Global CA". You see the certificate window showing up.

4. Click "Trust" to open trust settings.

5. Select "Never Trust" option in the "When using this certificate" field.

6. Close the certificate window to save the change.

Now you will see the "Not secure" message in Web browser on Websites that use certificates signed by "GeoTrust Global CA".

⇒ Import Root CA Certificate into Mac

⇐ Delete Root CA Certificate from Mac

⇑ Managing Certificates on Mac Computer

⇑⇑ Apple Mac Certificates Tutorials