Google added a way to export a report that shows you who has access and what level of access they have to your AdWords account. Over the years, I am sure many of you have given access to your AdWords account to various colleagues, consultants and friends but sometimes you forget to remove their access or limit their access. This report summarizes what access they have.
Google said on Google+:
As a manager account user, have you ever wanted to quickly see which AdWords accounts a user has access to? We’re introducing a new report to make it super easy to view user access information across all your managed accounts.This report provides a top down view of all the users with access to the accounts in your manager account. It shows each user’s permission levels, their last login date, and the specific account they have access to. To download the report, go to the Account Access page under Account Settings in your manager account.
Here is a picture of the report export tool:
More details on how to use this can be found in this help document.
Forum discussion at Google+.