By Amit Pratap Singh , India

Open up a terminal (Ctrl+Alt+T).

Type uname -r . This will show you the kernel you're using currently, so you don't want to remove this.

Run the following command:  dpkg --list | grep linux-image . This will show the all the kernels that are installed.

Note down the names of all the kernels which you want to remove.

To remove the kernels, run:  apt-get purge linux-image-x.x.x.x-xyz  (replace the kernel name with an appropriate one).