Hi sarwiya,
The way I understand your statement above, I believe that you want to remove the new custom styling that you did and bring back the default style. So, kindly remove this line of code in your custom.css:
#top .mobileMenu{
background-image: url(http://sarwiya.com/work/wp-content/themes/pixelgray/images/icons/menu.png);
background-attachment: initial;
background-position: left;
background-position-y: 48%;
background-origin: initial;
background-clip: initial;
background-color: transparent;
background-size:26px 26px;
background-repeat:no-repeat;
-moz-background-size: 26px 26px;
-webkit-background-size: 26px 26px;
width:100%; margin:0px 0 -5px 0; max-width:767px;
padding:20px;padding-left:35px;border:none;
border-bottom:1px solid #999;border-top:0px dotted #333;
}
If there are other styling that you have applied to it, just remove it from either custom.css or Quick CSS. Hope this helps. :)
Regards,
Ismael