Remove report subscriptions for terminated users

Good Day,

I'm trying to figure out a way how to remove/cancel report subscription for users who are no longer with organization.

AD account for the termiminated user(s) is set to disabled with no active licenses. 

By default (company policy) all emails for ex-employees are forwarded to a desiganted user/email box, which getting overwelmed with failed subscriptions.

Thank you in advance for your advise.

Sam