It really isn't stealing. It's not copy right protected for it to be stealing, so ignore the girl who answered before me.
You do have to have general knowledge of HTML to be able to remove it. In which case, it's pretty simple.
<a href = "URL TO WEBSITE">
That is used to make a picture of word(s) into a link. So that when you click it, it sends you to the website they entered. If you delete that, then it will disable the link.
It will still leave the picture or words that were used though.
To remove the picture/words, you have to find them.
The codes for these ads are usually found in the top and bottom of the code.