Error 404 not found while using command sudo apt-get update - PPA shimmerproject has no release file

I am getting an error while using the command :

sudo apt-get update

The error:

How can I solve it?
since i am new to ubuntu i really dont know much so please help me

This message indicates that you have added a PPA that doesn't contain a proper file for your Ubuntu version. You can fix this problem by simply remove the PPA that cause the problem (note that no new software will be added), then find the proper PPA location and add it.

To remove a PPA:

sudo add-apt-repository --remove ppa:whatever/ppa

in your case try:

sudo add-apt-repository --remove ppa:shimmerproject/ppa

and then

sudo apt update