Change a variable product to a simple product

I imported a product from Aliexpress that had 30 variables with Aliexpress Dropshipping and Fulfillment for WooCommerce.

As it is a variable product, on the product purchase page there is the drop-down bar to choose ‘Color’ (because it is marked as an attribute), but in all products there is just one option, so I would like to remove that drop-down bar.

I have tried to put the product as simple, and it works … BUT I do not get the supplier’s inventory.

My questions are:
-How can I remove the drop-down bar of the variable product (because it does not make sense that you go to buy a product and check the same). (I have tried to remove it but when I remove it I do not get the supplier’s inventory)

or
-How can I put the inventory on the simple product synced with Aliexpress.
(I have tried to check the option of ‘Inventory management’ in Edit product, but the inventory of the Aliexpress supplier is not synchronized.)

Thank you very much in advance.