In order to add/remove Permissions, you must be an Admin within your account.
The admin should log on to https://app.carnivalmobile.com/#/apps/portfolio with your credentials.
Once you login, navigate to the "My Team" screen, which is located under Settings:
On the top left, click "Create Permissions" and enter the person's email and what roles you wish them to have:
Then click Create and you're all set!