It is recommended to remove old kernel version to clean up the boot menu and to get some extra disk space.
1. Check which kernel version you're using:
2. List all installed kernels and headers on your system:
dpkg -l | grep linux-image
dpkg -l | grep linux-headers
3. If you're not using the latest kernel version, try rebooting your system first.
4. You can remove old kernel versions automatically:
sudo apt-get autoremove
5.a. Or you can remove them manually one by one:
sudo apt-get purge linux-image-x.x.x.x-generic
Be sure, NOT to remove the version you're using!
It is also recommended to leave the previous version on your system.
5.b. When you're done, update your Grub:
6. Reboot your system.