XU4 howto remove kernel 3.x after upgrade to 4.9?

How do I remove the 3.x kernel?
apt-get dist-upgrade will update:
The following packages will be upgraded:
linux-image-3.10.105+

Meveric (who maintains the apt kernel updates for Odroid’s), will change that package to 4.9 at some point in the future.

Until then, 4.9 is still in testing and you will need to hold current kernel package to prevent it overwriting 4.9:
https://github.com/Fourdee/DietPi/issues/926#issuecomment-306546305