If you want to delete an empty and unused portfolio, you can do so in your online account (desktop) by opening the portfolio, then going to 'Options' and selecting 'Delete portfolio' (see video below).
Please note: If you have an empty portfolio that has been funded and traded, you can not delete this portfolio. You can, however, 'Hide' empty portfolios that have been funded, please see below.
To hide a previously funded portfolio, simply hover over the portfolio name on your dashboard, then click the three dots that appear on the left, and finally click 'Hide'.
You can always unhide previously hidden portfolios by clicking 'Hello, Name!' in the right top corner -> Settings -> Hidden portfolios -> toggle a switch next to the portfolio you wish to unhide.