How to clean Ubuntu's /boot if it has run full

After some time a kernel update may tell you something along the way of "Hey, there is a kernel update, but I can't update it because there is no space left on /boot".

To solve this you'll have to do a little apt-cleaning.

First find out which kernel you are using at the moment with

After this get the list of currently installed kernels with

Now remove all kernels except the current and maybe the one before that by using

When you are done with removing, clean up orphaned dependencies with

And you should be done. You'll likely have to do this every few months again I'm afraid.