The Portfolio page is where users may go to redeem their lends for the full principal plus interest amount.
If you have lent tokens in a market, you can claim your full principal plus interest payment once the market has matured and the redemption period has opened. You may do so by selecting "Redeem" (highlighted in red) under "Actions" in the "Open Positions" table. Note that the "Redeem" button will be greyed out until after the redemption period has opened.
The amount you can redeem is determined by the amount of qTokens your wallet holds. Upon redemption, your qTokens will be burned at a 1:1 ratio in exchange for the actual underlying token.
By convention, the redemption period is set to be 8 hours after the maturity time to allow a grace period for borrowers to repay their loans. Once the repayment period is open, it will remain open forever so you can redeem at any time.
The "Portfolio" page also lists the status of your live, open Quotes, if you have published any. You may cancel your Quotes anytime on this page by selecting "Cancel" under "Actions" in the "Open Quotes" table.