Add these codes to the Custom CSS box and Save
Product Block
/* Product Block */ div.product-block div.product-quantity-input { display: none !important; }
Shop – Category Page
/* Shop - Category Page */ body.view-list div.product-quantity-input { display: none !important; }
All Products
/* All products */ div.product-quantity-input { display: none !important; }
Cart Page
/* cart page */ .cart-row-qty { display: none !important; }
Specific Products
With specific products, first, you need to create a tag with the name: nqt
Next, assign this tag for products where you want to remove the quantity then use code to Custom CSS box
/* Specific Products */ .tag-nqt div.product-quantity-input { display: none !important; }
One Product
#1. You need to edit the product where you want to remove the quantity > Additional Info > Add a Code Block
#2. Paste code to Code Block
<!-- One Product --> <style> div.product-quantity-input { display: none !important; } </style>