Inviting a New User:You can invite others to gain access to your Google Merchant Center account from the Users tab under Settings. These invited users sign in to your account with their own logins, so you can safeguard your own login information. To grant access to additional users, follow these steps:
- Sign in to your Merchant Center account.
- Click the Settings tab.
- Select Users.
- Click the + User button.
- Enter the email address of the person you want to invite.
- Select the access level you’d like to grant to the user.
- Click Save.
For more information please follow the link below. https://support.google.com/merchants/answer/1637190?hl=en