[coisasdavida]

Activation Lock is never dealt at Store level. There is a website specifically for this and the customer should start the procedure online.

[coisasdavida]

Start a request at the end of this page, https://support.apple.com/en-us/108934, if it gets that far, but I would exhaust all options first.

Should look into account password first. If he has started account recovery, Activation Lock removal will fail.