You can delete an imported certificate when the certificate has expired or when an encrypted connection is no longer necessary.
If you obtain a certificate using a CSR created from Web Config, you cannot import a deleted certificate again. In this case, create a CSR and obtain a certificate again.
Access Web Config, and then select the Network Security tab. Next, select SSL/TLS > Certificate or IPsec/IP Filtering > Client Certificate or IEEE802.1X > Client Certificate.
Click Delete.
Confirm that you want to delete the certificate in the message displayed.