You can unlink your Twitter or Facebook from your Tinychat account by logging in to your account settings, and visiting the Linked Services page. Here you can click "Unlink" for Twitter or Facebook. 

You can then visit your Facebook App Settings or Twitter App Settings if you wish to remove Tinychat from your Facebook or Twitter accounts.

Note: If you use Facebook or Twitter to login to Tinychat, and haven't set a password, you may need to reset your account password before you'll be able to login again in the future.