removing old kernels does not cleanup the /boot partition
 

Hallo.
I am booted into 5.4.0-104-generic

I wanted to get rid of the old kernel versions, to free some space and keep my system clean.

Since the "autoremove" options seems to do nothing, I tried

sudo apt-get remove --purge linux-image-5.4.0-81-generic

In the /boot partition, actually, the files
initrd.img-5.4.0-81-generic
and
vmlinuz-5.4.0-81-generic
disappeared, but I still have the files
config-5.4.0-81-generic
vmlinuz-5.4.0-81-generic

Why this?
Can I safely rm them?

If you can boot successfully with the new kernel and all the hardware works, you can delete anything that belongs to the old kernel. Though I'm puzzled that you name vmlinuz-5.4.0-81-generic both as a file that was cleared and as one that remains on disk. Maybe you meant System.map-5.4.0-81 the second time around.

The modules that went with the old kernel will form a separate package which you might also want to remove.

Yes, correct. I meant that. Thanks