check current kernel uname -r 4.4.0-96-generic view all kernels ls -1 /boot/ System.map-4.4.0-89-generic System.map-4.4.0-92-generic System.map-4.4.0-93-generic System.map-4.4.0-96-generic abi-4.4.0-89-generic abi-4.4.0-92-generic abi-4.4.0-93-generic abi-4.4.0-96-generic config-4.4.0-89-generic config-4.4.0-92-generic config-4.4.0-93-generic config-4.4.0-96-generic grub initrd.img-4.4.0-89-generic initrd.img-4.4.0-92-generic initrd.img-4.4.0-93-generic initrd.img-4.4.0-96-generic lost+found vmlinuz-4.4.0-89-generic vmlinuz-4.4.0-92-generic vmlinuz-4.4.0-93-generic vmlinuz-4.4.0-96-generic purge old kernels sudo apt-get purge -y linux-image-4.4.0-89-generic linux-image-4.4.0-92-generic linux-image-4.4.0-93-generic you may need manually to delete if disk is full sudo rm /boot/initrd.img-4.4.0-89-generic