Check your current image
uname -r
I'm on linux-image-4.4.0-62, thus I'll erase the others.
dpkg --list 'linux-image*'
sudo apt remove linux-image-4.4.0-47-generic
sudo apt remove linux-image-4.4.0-51-generic
sudo apt remove linux-image-4.4.0-53-generic
sudo apt remove linux-image-4.4.0-58-generic
sudo apt remove linux-image-4.4.0-59-generic
sudo apt autoremove
sudo update-grub