By naming another user as a delegate on your Gmail account, you give them the ability to read, send, and delete emails, and manage your contacts. This solution is more convenient and secure than giving a user your password to access your Gmail account. Learn how to grant or revoke delegated access and how to sign in as a delegate.
How to share access to your Gmail account – Delegated Access
A designated delegate can access your Gmail account for limited purposes. They can’t view or change important account settings. Here’s how to name a delegate.
Click on the settings icon in the top right corner of the screen.
Select 'Show all settings' from the menu that appears.