我的mac 10.15.1无法删除系统根证书，有人可以帮忙吗？
我无法删除证书，也无法更改钥匙串文件的read-only状态。
步骤：
RecoveryModeTerminal：
csrutil disable
NormalLoginTerminal：
su
security delete-certificate -c "SomeExpiredCert" /System/Library/Keychains/SystemRootCertifictes.keychain
响应：
security: SecKeychainItemDelete: UNIX[Read-only file system]
NormalLoginTerminal：
chmod -R 777 /System/Library/Keychains
响应：
chmod: Unable to chage file mode on /System/Library/Keychains: Read-only file system
chmod: Unable to chage file mode on /System/Library/Keychains/EVRoots.plist: Read-only file system
chmod: Unable to chage file mode on /System/Library/Keychains/SystemRootCertificates.keychain: Read-only file system
chmod: Unable to chage file mode on /System/Library/Keychains/SystemTrustSettings.plist: Read-only file system