Yes, while logged into your account you have complete visibility over your sub users.
Click "Users" and you will see a list of sub-users on your account
To Login as a particular user to the far right of their name you should see an icon that looks like keys. When you click on it you will be logged in as that sub-user.
- If you don't see the sub user on the first page, you can also filter by name/email address, "Find User", or "Login as user".
- If you click "Users" and don't see the list of users on your account, but instead see empty boxes under Name and Email, click the red arrow to the far right and you will then see your list of users.