Did you convert the request to a project? If so, you can add the template you want and delete the tasks from the wrong template.
I imagine there might be a report that checks for which template was used for creating the project - which is fixed in this case (which makes sense).
To that point, It would be great to be able to restrict which templates can be used to make projects and which templates are only used by attaching to existing projects.
At the bottom of the Project Overview, there is a section that shows the originating template‚Ä¶ if the project was made from a template.
If you catch it before the user gets to far, they can simply go back to the request and re-convert the request to the correct template. This will disconnect the resolved-to link from the first project, and you'll have to delete the first project.