Step 1: On your Staking screen, hit the ellipsis icon next to Staking balance. Choose Unstake. This will allow you to unstake from a validator/collator/ but still keep your funds locked.
Step 2: Enter the amount you want to unstake and hit Next. Key in your password then press Confirm. Your transaction is successful.
Depending on the network, your unstaked tokens can be withdrawn to your transferrable balance after a certain amount of time (approximately 7 days in Kusama, 14 days in Aleph Zero, 28 days in Polkadot and HydraDX). The clock on the Withdraw button shows you how much time is left before you can withdraw your unstaked funds.