Starting with v201506 of the AdWords API, you can:

• Hide or unhide an AdWords account under your manager account by setting the isHidden attribute of its ManagedCustomerLink to true or false, respectively.
• Exclude hidden accounts in ManagedCustomerService.get and ManagedCustomerService.query calls by specifying ExcludeHiddenAccounts = true in your predicate or AWQL WHERE clause.

With these new features, you can hide old or inactive accounts to reduce clutter in your managed account's dashboard, as well as detect and exclude hidden accounts using the AdWords API.

As with the AdWords user interface, you can only hide or unhide AdWords accounts. Any attempt to hide a manager account will result in a ManagedCustomerServiceError.CANNOT_HIDE_OR_UNHIDE_MANAGER_ACCOUNTS error.

Don't worry -- hiding an account doesn’t affect serving:

• You can always unhide an account by setting the isHidden attribute of its ManagedCustomerLink back to false.
• You can retrieve all of your accounts by setting ExcludeHiddenAccounts to false in your selector, or by not specifying a predicate on ExcludeHiddenAccounts.
• Ads in hidden accounts will continue to serve.

More manager account resources

• Guide on managing customer accounts.
• Latest docs on ManagedCustomerLink and ManagedCustomer.

Still have questions? Feel free to visit us on the AdWords API Forum or our Google+ page.

- Josh Radcliff, AdWords API Team

Source: Google Ads Developer Blog