You may consider following the procedure from this blog post
to combine both toolings.
1. Usually the root of the project you are seeing in the AppBuilder clients corresponds to the www
2. I'd suggest that you create a blank project and manually add your files.
3. Usually you can import an AppBuilder project and restore if from ZIP as explained here
. However, I am not sure if this will succeed with an Ionic project, but you can try with creating a project from the blank template and manually readjust the files with your Ionic project files.
You may also need to import any plugins. Please examine how to work with plugins
I hope this helps.
Telerik by Progress