You can delete the imported CA Certificate.
Enter the printer's IP address into a browser to access Web Config.
Enter the printer's IP address from a computer that is connected to the same network as the printer.
You can check the IP address of the printer from the following menu.
Settings > General Settings > Network Settings > Network Status > Wired LAN/Wi-Fi Status
Enter the administrator password to log in as an administrator.
Select in the following order.
Network Security tab > CA Certificate
Click Delete next to the CA Certificate that you want to delete.
Confirm that you want to delete the certificate in the message displayed.
Click Reboot Network, and then check that the deleted CA Certificate is not listed on the updated screen.