New to DevOps, trying to find IAM references within codebase

Hello all,

i am new to DevOps, i have opened it before, but I have a new role and with it a bunch of security and other roles.    I work in an AWS based shop, and when cleaning up old IAM accounts for users who are no longer here, I ran into an issue.

Even though a user has long since been disabled then deleted in Active Directory, so most other ties are long gone, there are connections to Azure Devops from AWS IAM.

I was told this was a simple search, but struck out, as did google (admittedly my google-fu leaves a bit to be desired) and 2 of the devs i work with, when trying to search the code base for references to either the FULL length arn:aws:iam::(companyacctnumber):user/username or just username, so we can find what apps are still tied to certain users, as I disabled a IAM for a user who had been gone for over a year and blew up a piece of software running in Azure.

If you have an answer please be specific in steps as this is NOT a tool i have done more than open and look at a couple times as I am NOT a developer.

Thanks in advance