I received this response from StackOverflow before they flag my question...
Check the current kernel version with uname -r and make sur that the current kernel work without any problem to keep it.
From the terminal:
List the installed kernel :
dpkg --list | grep linux-image
dpkg --list | grep linux-headers
Remove the old kernels through the following command:
apt-get purge linux-image-x...
apt-get purge linux-headers-x...
using the synaptic package manager
Open Synaptic and mark the old kernel versions for removal then apply changes
from the Update Manager view the Linux kernels , click the 'Remove' button for the kernels that you want to remove
You can install the purge-old-kernels cli tool through:
sudo apt-get install bikeshed
If you want to purge the old kernel except for the latest 2 kernels, run the following command:
sudo purge-old-kernels --keep 2