Connectcore 6 Firmware problem

Dear Sir or Madem,

My connectcore 6 ,install Yocto demo image for emmc now no problem but how uninstall Yocto Project and new install Ubuntu image?. Where isthe ubuntu type image (Lubuntu, Kubuntu).

there is no ubuntu or kubuntu for cc6. You can build customized Yocto image similar to the demo you are talking about. you can find instructions here:

In that case, can I rebuild the whole Ubuntu from source and install it onto digi ConnectCore 6?

sure, why not. You’ll just have to figure out hot to integrate cc6 kernel/device tree/bsp in to it