For deleting a Portfolio please perform the below described steps:
On Mobile app:
Go to Portfolio tab
Tap 3 dots on the top right corner
Select "My Portfolios"
From the portfolios' list swipe left the one you wish to delete and then confirm
If you're not already logged in to your CoinStats account, login by clicking the respective button on top right of the screen.
After logging in choose Portfolio.
Hover over the portfolio name you wish to delete and you'll see the small delete button. Click on it and confirm to delete.
Please note that the action of deleting a portfolio cannot be reversed.