If you haven't read about what associated wallets are and how they can be used, you can head over that article here.
Navigating to remove a wallet
Click on the identicon in the top right of the page
Click on your username to navigate to the Account Details page
Click on the "Wallets" tab
Removing a wallet
To remove a wallet, all you have to do is click the "x" next to the wallet you want to remove. You always need at least one wallet associated with your account. Once removed, you will no longer be able to log in with the removed wallet.
Please reach out to the team if you have any issues!