Within Teamwork.com, you can detach files from the tasks on your projects.
Go to the List area of your project and select the relevant task to open the task details view.
You will see a list of the attached files below the task and an option to Manage Task Attachments.
In the file management modal, select the trash can icon to the right of the task, then click Save Changes to apply the change to the task.
For more information, see: Adding a File to a Task