Mobile Layout – Dont show an image -

Hi again.. it has been long time since last time you help me with the theme.
I need you again friend.. Let me explain to you:

If you go to my website: http://www.sugar7.eu/10503 you will see in the header the logo on the right side and on the left an image of pallets. Ok what i need is when somebody visit the website on his mobile, this image disappear. I know i have to modify the css but i have no idea my friend.. Could you please tell me step by step what should i do.

Blueowl dont do it by your own, I want to know how to do it please..
Thank you so much in advance my friend..

Look forward to hearing from you again.. xD