Overview:
If your product options do not require inventory tracking, then you will want to ensure that they do not ever go out of stock. This can be done by following the tutorial below.
Tutorial:
To change the inventory tracking, edit the product in the Products tab of your store and scroll down to the Inventory Section.
Uncheck the Track quantity checkbox:
Or if your product has variants then, select all and click the Open bulk editor button:
If the Bulk Editor doesn't have Track Quantity, then click the Add fields button and select Track Quantity under the Inventory section:
Then change the Track Quantity field for each to Don't Track Inventory: