It seems to be a lock by the Registrar, but it can be removed.
clientTransferProhibited
client transfer prohibitedThis status code tells your domain's registry to reject requests to transfer the domain from your current registrar to another.
REGISTRAR-LOCK is a status code that can be set on an Internet domain name by the sponsoring registrar of the domain name. This is usually done in order to prevent unauthorized, unwanted or accidental changes to the domain name.