How to replace a PAE kernel with non PAE Kernel?

To install a different kernel (such as a non-pae kernel), you would need to install the package for it. Use your favourite package manager (like Synaptic) to install linux-image-generic, or use this command in a terminal:

sudo apt-get install linux-image-generic

In Ubuntu 12.04 or earlier version, this will install the latest generic kernel that is not pae. Then you would need to reboot and in the grub menu select the non-pae kernel. Once it boots up, verify everything is working.

In Ubuntu 12.10 or later version, this will NOT work since linux-image-generic is equivelent to linux-image-generic-pae.

Optional: You can remove the other kernel once you know everything is working with the new kernel by doing

sudo apt-get remove linux-image-generic-pae