You need to be looking for the following which is located in default.php on line 29
.hitcounter_container {
background-color: #FFFFFF;
border: 1px solid #DADADA;
padding: 10px;
}
and remove border: 1px solid #DADADA;
from it.
As for removing the "Created by" text, please ensure you are allowed to remove it before I answer how to.