Disk full; Terminal in Recovery mode won’t delete files; boot kernel panics
In spite this post is old, I decided to leave my solution here to help community with one more approach. 

note: I wrote a medium with more description.

In my case, I din't have that extra partition available so, in recovery mode: 


Run the terminal

 
run diskutil list


 


Find the identifier of "VM" volume. In the case of the previous image is "disk1s5". You'll probably have "disk2s4"
delete the volume VM: 


diskutil apfs deleteVolume disk1s5 

(replace the disk1s5 for your VM identifier)


You are now able to remove files on "/Volumes/Macintosh HD"


I hope it helps someone.