I need to get more information so I can help you. What do you mean by interfaces with no data for the last 3 months? Do you mean the interfaces that have been down for the last three months?
We want to know the switch ports with admin status up with no data for the last three months. (operating status down). After that we have that report we have to disable those ports.
We don't have this report OOTB, but we have the data. You can look at some of the report on the content exchange here and you might be able to use one of these as a template to tweak and get what you want.