In the "Manage your account" panel select item "My domains", "Services" menu.
In the appeared table click on the domain to be unlocked.
Click "Modify" on the domain page in the "Manage your account" panel in "Whois contacts" line of "Settings" table. On "Data update" page click on "Edit". Specify the new, earlier confirmed e-mail address and click on "Save changes".
Ensure that the new e-mail was earlier validated – domain will no longer have E-mail not validated" status.