Frequently Asked Question
First check your kernel version, so you won't delete the in-use kernel image, running:
uname -r
Now run this command for a list of installed kernels:
dpkg --list 'linux-image*' | grep ^ii
and delete the kernels you don't want/need anymore by running this:
sudo apt-get remove linux-image-VERSION
Replace VERSION with the version of the kernel you want to remove.
When you're done removing the older kernels, you can run this to remove ever packages you won't need anymore:
sudo apt-get autoremove
And finally you can run this to update grub kernel list:
sudo update-grub
First we need to free up some space. Carefully delete 2 of the older kernel packages with a command similar to the below, but with old version numbers from your system returned by the above section List Currently Installed Kernels.
rm /boot/*-3.19.0-25* rm /boot/*-3.19.0-33*