Your issue seems to be a different one than OP's. In your case, you have a product with no variants so your theme displays a single option for your variant dropdown. You can amend this by going to your product template file and altering the code which displays the dropdown selection. There you can create a condition where if a product has only one variant, then the dropdown will not be displayed at all.
You can find an example with reference code for that over at Shopify Docs: