When renaming a tear sheet, click the tear sheet you are wanting to edit in the left-hand panel and make sure you are under the Template builder tab at the top of the screen. Next, click the settings icon on the top right of the template builder, as highlighted in yellow below.
Now, you will be prompted with a window, as shown below, where you are able to edit the name of your tear sheet. Once done editing, click the blue Save button at the bottom.
Note: You can also change which of your portfolio companies are being included on this tear sheet in the dropdown window below the Template name window.