> In practice you can take rights away (obviously)
You can infringe rights; that's not the same as taking them away. There is a clear difference between having the power to do something and having the right to do it. There is nothing unusual about having the right to do something but lacking sufficient power to accomplish it. A right does not disappear merely because one lacks the power to prevent it from being infringed.
As the name implies, rights are fundamentally about right and wrong: they are expressions of how one ought to act, or respond to another's actions. Saying that a right exists is the same as saying that your own actions ought not infringe that right for others. Practicality is irrelevant. The "theory" (or rather, philosophy) you've casually dismissed is the entire point of the exercise.
Of course one needs power also, if only for self-defense, but power—or lack thereof—does not dictate right and wrong. Power merely expands the range of options available to you. Your rights—the things that it would be right for you to do—are the same whether you are powerless or omnipotent.
So what exactly are your rights? Well, that's for you to decide. Even true omnipotence wouldn't be enough to grant anyone else the power to make that decision for you.