Culling old versions of Kernel from /usr/lib/modules/

[KCB Leigh <kcbl2003@yahoo.co.uk>]

This message is related to the 'Re: solution to / full' thread.

I am running my computer from a Debian 11.6 OS on a 25GB partition on
a USB stick.  The root partition is now 70% full, with over 4GB (16%) of
the volume occupied by /usr/lib/modules/ (3.5GB) &
/usr/lib/x86_64-linux-gnu (1.4GB) - as far as I can tell, this latter
directory only has essential, current files.  I have been using this
volume for over a year, & the modules directory now has over a
dozen kernels from previous versions of the operating system.  I can
see the need to retain the last couple of versions, but within the
space constraints, I really cannot afford to keep all of these old
kernels, each consuming 307-323MB.

MY QUESTION:
- Is there some utility that pares these files, or must one do this
  manually?
- I have been reluctant to do this manually because I'm not too
  familiar with the structure of the operating system & do not want to
  delete a file which may be required by some other part of the system
  that I've not also removed.  Specifically, in the /boot/ directory
  there are also files related to these older kernel versions:
    config-5.10.0-*-amd64    (236 kB each)
    initrd.img-5.10.0-*-amd64    ( 72.7MB each)
    System.map-5.10.0-*-amd64    ( 83 bytes each)
    vmlinuz-5.10.0-*-amd64    (  6.8MB each)
  corresponding to each of the dozen or so old versions of kernel in
  the /usr/lib/modules/ directory.  I would think the older versions
  of these files should also be removed when the kernels are.
? & are there any other files related to these kernels that should
  also be deleted?  I think there is some file that contains the list
  of possible boot volumes displayed by grub: I think I've found this
  somewhere in the distant past, but can't recall whether it contains
  a list of these older kernels, or whether that list is dynamically
  updated depending on what is found on the boot volume.

I would appreciate any references that might give more information
about this, or any advice.

With thanks in advance,
Ken

(I have not subscribed to the list, but will try to check it; I would
be very grateful if replies could be cc to my e-mail address:
kcbl2003@yahoo.co.uk.)