Check if OS is 32- or 64-bit:

uname -m

Find os name and version (one of these should work):

cat /etc/os-release
lsb_release -a
hostnamectl

Find Linux kernel version:

uname -r

Disk space report (in human-readable format):

df -h

List kernels:

apt list --installed | grep linux-image

Then delete a problematic kernel:

sudo apt remove kernel-name

(where kernal-name is the part before the / in the previous results, e.g. "linux-image-6.8.0-47-generic").

Exit (or re-enter) graphical mode, useful for installing NVidia updates:
enter graphcal mode:

sudo systemctl isolate graphical.target

exit to command line:

sudo systemctl isolate multi-user.target