After the certificate is issued, the number of available SANs (hostname slots) cannot be decreased. You can, however, change the used hostnames via reissue.
Another solution is to request cancellation and refund of the existing certificate within the acceptable refund grace period (15 days after the first issuance within 90 days after the purchase date) and purchase the new one with the correct amount of additional domains.
IMPORTANT NOTE: The validity period and cost of any extra SANs (Subject Alternative Names – further domains added to the Multi-Domain SSL certificate), bought following the initial certificate purchase will not be prorated.
What does this mean?
- If you add a SAN to the Multi-Domain certificate after purchasing, it will be the same price as the SAN added to the Multi-Domain certificate during the initial purchase;
- The SAN will have the same validity period as the certificate it is attached to regardless of when the additional SAN was purchased.