To delete a tear sheet template, first select the tear sheet on the left-hand panel and make sure you are under the Template builder tab at the top of the screen. From here, click the settings icon on the top right corner of the template builder, as shown below.
Next, click the Delete button on the bottom right of the window shown below.
Finally, click the red delete button on the next window, as shown below.
Note: As explained, this will permanently delete this template and any generated tear sheet from this tear sheet.