Find the market by either going to the market page or portfolio and hit the Remove Liquidity button.
This will bring up the remove liquidity modal. You'll first need to approve the removal so your removal estimates can be brought in. Sign this transaction in your wallet.
Once approved you can see what you'll receive. Removing liquidity may return shares; these shares may be sold for USDC if there is still liquidity in the pool. Winning shares can be redeemed for USDC after the market has finalized.
Hit the Remove All Liquidity button to bring up the confirmation screen.
Any shares you were given can now be sold. You can view these in the positions tab of your portfolio or the market page.
If left with positions after you the market has finalized, you can cash these out using the Cash Out Shares button in the portfolio.