Using the Blade tool on a Final Cut Pro template normally creates retimed instances of the entire template. If you'd like to use only a portion of the project, be sure to wrap the template in a Compound Clip before cutting it – right-click it on the timeline and select New Compound Clip (or select it and press Alt+G). Once you've done it you can freely cut the newly created Compound Clip, retime it or perform any other operation as you normally would with a plain video clip.
You can make adjustments to the template itself (for example: replace an image on the Drop Zone, change text, etc.) after it has been placed in a Compound Clip by double-clicking into it. To return to your project, click the small "back" arrow above the timeline. The Compound Clip will be also added to your library (to the event selected when saving it).
Note that most of our newer templates are Modular Templates, which means they come with pre-made separate modules based on the main project generator, which makes it easy to use parts of the project without Compound Clips.