How did you initially add the Shop Pay Instalments banner on your store? Did you perhaps duplicate your theme, prior to adding the banner?
If this is the case, you can look into publishing the other version of your theme, before the Shop Pay Instalments banner was added. Just a note though that if you’ve recently added any new apps onto your store, you might need to double check if the apps’ functionalities appear on the older theme.
If you prefer to continue using your current theme, but to remove the Shop Pay Instalments banner code from it, you can take a look at our theme guide here to see which relevant code will need to be removed. Because this lies outside the scope of support of Shopify staff however, if you need help with removing the relevant code you can look into contacting one of our Shopify Experts.
Was there a particular reason that you’d like to remove the banners from your product pages, but to remain offering Shop Pay Instalments on your store?