Customer can't remove Product Addon

[Wabun]

Just a quick question, why is it that a customer can't remove a Product Add-on. WHMcs recommend to create a Product Add-on for a Static IP, but customer want to drop this, but there is no option for him to remove it.

 

Now I have not only this problem, but also need to remove it myself from the admin side and refund the charge because as usual customer paid and was not able to remove it.