I have an add-on question.

I currently have a PS4 platform version and a Steam platform version of ARR. Would it be possible to cancel the Steam version as if I never had a "PC" platform, while keeping my PS4 version, then adding a normal PC version to my account? If so, how would I go about this? I couldn't find any type of game cancellation button on Steam, but I'm also not very familiar with their website.