No, you can’t modify the name of a registered domain. You will need to register a new domain name. At which point you will be the owner of both domains. Simply let the renewal of the old domain lapse if it is no longer needed.
There is a caveat to the above statement. If a domain name is less than 5 days old, it is possible to have the domain deleted from the registry and a new domain name registered. This attracts a nominal fee.