Can we return a pkg at your station or can you pick up a pkg to return to Amazon at our home in Sparks, NV?

I don't think Amazon Fulfillment Center take consumer returns. There's should be an authorized Amazon return store in the Reno area, like Kohl's, UPS Store or somewhere similar

I would call amazon support in the app

If you don't finish delivering a package for Amazon flex I'm assuming then you will have to return it that day or before 10:00 a.m. the next day