combine backgrount image

In gtmetrix show the following message

The following images served from kelekis.gr should be combined into as few images as possible using CSS sprites.

http://www.kelekis.gr/components/com_vi ... w_down.png
http://www.kelekis.gr/templates/gk_espo ... k-logo.png
http://www.kelekis.gr/templates/gk_espo ... opline.png
http://www.kelekis.gr/templates/gk_espo ... g_menu.png
http://www.kelekis.gr/templates/gk_espo ... _hover.png
http://www.kelekis.gr/templates/gk_espo ... g_main.png
http://www.kelekis.gr/templates/gk_espo ... bullet.png
http://www.kelekis.gr/templates/gk_espo ... is_nav.png
http://www.kelekis.gr/templates/gk_espo ... erface.png

Some photos are unneccesary how could combine or exclude?
I am using jch optimization and it have option but doesnt work

As far as I can see this is an automatic tool that doesn't work well. In the specific files it mixes png files from different styles, and it is impossible on one site to load 2 different styles . So the list gets shorter with at least 2 files.
Also creating a sprite consisting all those files might be impossible without additional html changes so they can be used as sprites.
Sadly, this kind of modifications are beyond our support.