It is no problem to cancel your SSL certificate. In almost all cases, you will be refunded your money.
Cancelling SSL certificate before it has been issued
Do you wish to cancel your SSL certificate before it has been issued? You can do this via your customer panel. After your cancellation, you can enter a new CSR or cancel your request entirely and be refunded.
Cancelling SSL certificate after it has been issued
Do you wish to cancel your SSL certificate after it has been issued? You can do this until 14 days after issuance. When you cancel, you are immediately refunded and the SSL certificate will disappear entirely from your customer panel. If you're using the Versio API, you can be refunded until 20 days after issuance. This is to give the resellers of Versio a transition period to process the cancellations of their customers.