use the below change the $userid to whatever the variable is that has the id. This depends on how your creating the dynamic checkbox. When you pull the data from the database you need a while loop to display the data inside the form tag.
... more code should be here like connection and db selection
$query = "your query here";
while( $input = mysql_fetch_assoc( $quer) )
{
echo "<input type=\"checkbox\" name=\"id[]\" value=\"$input['your_id_column_here']\" />";
}
sample of the input
<input type="checkbox" name="id[]" value="$userid" />
then just loop over it
if( isset( $_POST['id'] ) ) // only if post data is there
{
$ids = $_POST['id'];
foreach($ids as $id)
{
// remove from db or whatever you want to here
}
}