from here: https://www.linux.org/threads/solved-how-to-remove-old-kernels-in-kubuntu-20-04-kde.36151/?__cf_chl_f_tk=0CshtAQX9mOyYFgwlXwGqSaQg2c80WYKrnIzGqR5z.Q-1654529053-0-gaNycGzNBf0

after running the command to purge old kernels the recommendation is to run these commands


dpkg --list |grep "^rc"
dpkg --list |grep "^rc" |cut -d " " -f3
dpkg --list |grep "^rc" |cut -d " " -f3 |xargs sudo dpkg --purge
sudo update-grub
sudo update-initramfs -u

reboot and when it boots back up run
step 1 again to verify kernels were removed and

Code:

uname -r

to see what is currently running
just do not remove the kernel you are currently using