$query = "SELECT * FROM TABLE WHERE id = 7"; // 7 :)
$result = mysql_query($query);
$row = mysql_fetch_array($result);
foreach ($row as $key => $value) {
if (strstr($value, 5)) { // You want to find 5 in the item
$value = str_replace(5, '', $value);
$id = $row['id'];
mysql_query("UPDATE table SET $key = '$value' WHERE id = $id");
}
}