You can just set the range of the outro that you want to save using the in and out points below the preview monitor or the blue range bar above the timeline, then "File > Export movie as" making sure you select "Export range only" in the Export dialog. Bear in mind that you will not be able to modify the text after the export
The outro must be applied to a clip first but if you do not want any of the clip showing during the start of the outro then select the clip and outro and unlink it using the chain symbol, after which you can move all elements of the outro to an empty part of the timeline prior to setting the range and exporting.