Steps to upgrade Linux kernel
apt-get install linux-image-4.4.0-124-generic
apt-get install linux-headers-4.4.0-124-generic
update-grub
Delete old kernel(s):
sudo apt install byobu
View list of installed kernels:
dpkg -l | grep linux-image
sudo purge-old-kernels
update-grub
sudo purge-old-kernels
update-grub
By default, byobu will keep at least 2 kernel version on the system to ensure that you have a fallback kernel when the first one fails. If you want to keep the only one (the latest) kernel, then you can use the command below to remove all except of one Kernel:
sudo purge-old-kernels --keep 1 -q