I Solved the issue by editing the k2 css file, ill explain here the steps:
1. Go to yourDirectory/components/com_k2/css
2. Open the k2.css file with a file editor like NotePad++ (or whatever you have)
3. On the RSS Feed Icon Section, delete this code sentences:
3.1 div.k2FeedIcon {padding:4px 8px;}
3.2 div.k2FeedIcon a:hover {display:block;float:right;margin:0;padding:0;width:16px;height:16px;background:url(../images/fugue/feed.png) no-repeat 50% 50%;}
The first code line reffers to the position of the feed icon, the second one it's about the image.
If someone have doubts write here on the topic, apparently it's too much work for the developers and/or moderators/administrator of the k2 website to answer our issues... they never answer anything.