remove quantity select on product page

-- HikaShop version -- : 2.4.0

I sell courses, the customer can only buy one.

How can I remove the number box and + - next to "add to cart" button?

In the system configuration you have an option for that:
"Display the quantity field on the product page" in tab Main -> Product

Depending on your needs you might want either "No display", or perhaps "On a per product basis", where the latter allows you to leave or remove the quantity field for individual products just as you want.

Hi,

In Configuration > Display > Product, select "show simple" for the option "Quantity layout on product page"