Registrar Lock means that the domain has been locked, therefore it is not possible to carry out operations on the domain, for example change of maintainer.
To have it unlocked you need to contact the provider that manages the domain.

For domains registered with Aruba you can request to unlock the domain yourself and receive the 
Authorization Code  at the contact email address of the domain owner by logging in using your login and password at http://admin.aruba.it or by opening a ticket from the online support website, from the ‘Domain Transfer and Registration’ department.

As an alternative you can request to unlock the domain by sending the following documents by fax to +39 0575/862000, or by Ticket opened from the Aruba Support  website:

N.B. Please remember to indicate the email address, where you wish to receive the Authorization Code, on the form.  

Aruba reserves the right to request further documents in order to verify the identity of the persons involved.

**To complete the form correctly please see the Facsimile with relevant Instructions.

Attention! The 'Registrar Lock' Status does NOT concern .it domains nor .eu domains