Thank you for reaching out to the Shopify community.
The right way to achieve this would be via product tags as you need to hide quantity buttons only for certain set of products. The next steps here would be:
Add a product tag to identify the products where the quantity button has to be hidden.
Add a custom code in main-product.liquid (can vary based on theme) to hide the quantity buttons based on tags, happy to help if you can help with the theme name and the website URL to have a quick check.
You can create a new template to hide the quantity selector, but the implementation of quantity size dropdowns 1, 5, 10, and 15 will require the custom dev in your theme code.
Because this will not impact only at product page but we have to take this implementation to cart page also.
As the user can also change the quantity on the cart page.