Basic idea:
in the form:
Create checkboxes with the name the same as the id of the corresponding row in the table.
in the processing part:
Do the the same query as before to produce the same results. Loop through the ids and test isset($_POST[$IDCOUNT]). If the result is set, run a function which uses SQL to delete the row ...where id=".$IDCOUNT."...
You may also want to look at variable variables.