Pull info from the Sheet, and Add, Delete or List delegates
If you instead want to manage this with a user & password protected web app, go here.
Copy template to get Sheet with Google Apps Script.
Use the userDelegation script menu to list, add and delete delegates.
Add inbox accounts to list delegates for in column A of sheet Manage.
Add a user to column C to which you wish to Add the inbox in column A of sheet Manage.
Add a user to column D which you wish to Delete from the inbox in column A of sheet Manage.
The result of each action will be added to the sheet Log.
When using List and Add, the delegated accounts will also be listed in the sheet Delegated.
The Delete action only displays its result in Log.
secrets.gs needs secrets from a service account with domain wide access to the necessary scopes.
Read the wiki how you set that up.
The secrets.gs in the repo will never have any secrets, as that would give any user acess to my domain. Which is why you also shouldn't post your secrets publicly, and only give access to this sheet and script to trusted admins. Even if that's a given, it never hurts to remind people. :-)
tl;dr - No data is sent anywhere, except between you and Google.