To be able to publish signals you first need to create signals. You can read more about creating signals in the developer documentation.
After you have created signals through an integration they will appear under "Show all signals".
A single unpublished signal in "My integration".
If you would like to make that signal available for the rest of the organization and be used in timelines it needs to be published.
Click on the signal you would like to publish and click on the "Publish" button.
Review and edit the metadata before clicking the "Publish" button. The signal is now published as a Item.
Head over to the "Items" page for your organization and click on the Item you would like to update. You can now edit the metadata in the sidebar.
Unpublish Items (Delete Item)
You unpublish items by deleting them. Remember that this affects timelines in which the items is being used. Head over to the "Items" page for your organization and click on the Item you would like to delete. Click the context menu and then on "Delete item".