Uninstalling Linux kernel

# apt-get autoremove linux-image-4.8.0-52-generic
Reading package lists... Done
Building dependency tree... 50%
Building dependency tree
Reading state information... Done
Starting pkgProblemResolver with broken count: 1
Starting 2 pkgProblemResolver with broken count: 1
Investigating (0) linux-image-extra-4.8.0-52-generic [ amd64 ] < 4.8.0-52.55~16.04.1 > ( kernel )
Broken linux-image-extra-4.8.0-52-generic:amd64 Depends on linux-image-4.8.0-52-generic [ amd64 ] < 4.8.0-52.55~16.04.1 > ( kernel )
  Considering linux-image-4.8.0-52-generic:amd64 10001 as a solution to linux-image-extra-4.8.0-52-generic:amd64 0
  Removing linux-image-extra-4.8.0-52-generic:amd64 rather than change linux-image-4.8.0-52-generic:amd64
Done
The following packages will be REMOVED:
  linux-image-4.8.0-52-generic linux-image-extra-4.8.0-52-generic
0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded.
After this operation, 234 MB disk space will be freed.
(Reading database ... 428734 files and directories currently installed.)
Removing linux-image-extra-4.8.0-52-generic (4.8.0-52.55~16.04.1) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
run-parts: executing /etc/kernel/postinst.d/dkms 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
Error! Could not locate dkms.conf file.
File:  does not exist.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
update-initramfs: Generating /boot/initrd.img-4.8.0-52-generic
run-parts: executing /etc/kernel/postinst.d/pm-utils 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
Generating grub configuration file ...
Found theme: /boot/grub/themes/breeze/theme.txt
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.8.0-53-generic
Found initrd image: /boot/initrd.img-4.8.0-53-generic
Found linux image: /boot/vmlinuz-4.8.0-52-generic
Found initrd image: /boot/initrd.img-4.8.0-52-generic
Found linux image: /boot/vmlinuz-4.8.0-53-generic
Found initrd image: /boot/initrd.img-4.8.0-53-generic
Found linux image: /boot/vmlinuz-4.8.0-52-generic
Found initrd image: /boot/initrd.img-4.8.0-52-generic
Adding boot menu entry for EFI firmware configuration
done
Removing linux-image-4.8.0-52-generic (4.8.0-52.55~16.04.1) ...
Examining /etc/kernel/prerm.d.
run-parts: executing /etc/kernel/prerm.d/dkms 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
update-initramfs: Deleting /boot/initrd.img-4.8.0-52-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.8.0-52-generic /boot/vmlinuz-4.8.0-52-generic
Generating grub configuration file ...
Found theme: /boot/grub/themes/breeze/theme.txt
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.8.0-53-generic
Found initrd image: /boot/initrd.img-4.8.0-53-generic
Found linux image: /boot/vmlinuz-4.8.0-53-generic
Found initrd image: /boot/initrd.img-4.8.0-53-generic
Adding boot menu entry for EFI firmware configuration
done
The link /vmlinuz.old is a damaged link
Removing symbolic link vmlinuz.old
 you may need to re-run your boot loader[grub]
The link /initrd.img.old is a damaged link
Removing symbolic link initrd.img.old
 you may need to re-run your boot loader[grub]