in MySQL, the code for a recordset value is:
$row_RSName['ColumnName']
in MySQLi, the corresponding code would be:
$RSName->getColumnVal("ColumnName")
so your code would be:
<?php echo(str_replace("http://", "", $RSName->getColumnVal("ColumnName"))); ?>
to also remove https, create an array of the values to remove:
<?php echo(str_replace(array("http://",https://"), "", $RSName->getColumnVal("ColumnName"))); ?>