Delete old kernel Linux kernel in Ubuntu

Refer to this How to Remove the old (or new) kernels

http://ubuntuhandbook.org/index.php/2015/08/install-latest-kernel-script/

1. In Ubuntu with a graphical interface:

1.1 Installing synaptic Package Manager in Ubuntu Software Center

1.2 Deleting packages using Synaptic Package Manager:

• Click the Reload button in the want to remove the new kernel.
• Select Status-installed on the left pane to make search list clear.
• Search linux-image- using Quick filter box.
• Select a kernel image "Linux-image-x.xx.xx-generic" and mark for (complete) removal
• Finally Apply changes

2. Under the Ubuntu Server environment:

2.1 uname-r  Get current kernel version 2.2 Dpkg-l | grep linux-image-    

    Dpkg-l | grep linux-headers-   Gets the name of the currently installed package

2.3 sudo apt-get autoremove kernel_image_name  replace Kernel_image_name with the name you obtained in step two to delete.

Be careful not to delete kernel that need to be preserved.

Delete old kernel Linux kernel in Ubuntu