Within Teamwork Projects, you can disconnect your site from the Teamwork Projects for Chrome extension.
If you are experiencing problems creating items via the extension, it's a good idea to try disconnecting and adding your site again. You can do this by clicking the settings cog icon in the top right corner of the extension modal:
You will see all of the sites you are currently connected to listed here. Hovering over each one shows an 'x' that you can click to disconnect it:
For more information, see: Installing Teamwork Projects for Chrome