Can I change the Season or Linelist name?

Yes.

If you are not changing the Season Code, simply delete the current linelist in the If you  Linelist/Season setup page then re-add with the same code with the name updated.

First, update the code on the SKU to the new code first using Inventory > Mass Edit or through the Upload facility. 
Then delete the original linelist in the Linelist/Season setup page then re-add with the new code and name. The code must be exactly the same as the one attached to the SKU.