Within Teamwork Chat, you can update the settings for a project channel and update or remove the associated project.
When viewing a project channel, click the options button (three dots) in the top right of the message area and select Edit channel.

Changing the associated project
In the edit channel modal, you can select a different project from the Project dropdown.

Note: Once a different project is selected, the channel members list will be updated to only include users on the newly selected project.
Unlinking a project channel
You can also unlink a project from a project channel, reverting it to a regular chat channel.
In the edit channel modal, update the channel type by selecting either Public or Private before saving.

For more information, see: Creating a Project Channel