I created a non-scalable OpenShift application with a Diy cartridge, Mysql 5.5 and phpMyAdmin. Now I could set everything I need, saw that I can use the port-forwarding to access my database through my Mysql Workbenck. So I do not take more phpMyAdmin cartridge.
Then it would be possible I remove the cartridge phpMyAdmin and enable scalability so I can use my three gears free for this application?
You can not change a non scaled application to a scaled application, you would need to delete your application and start over.
Also, I don't believe that you can create a scaled application with the DIY cartridge.