Just one? I have plenty of those!
No, I wouldn't just up and delete her. I don't know how big your list is, mine is pretty small - only about 2.6K, but even with that snall list, if you asked me to keep track of all people who open my email but do not sign up for anything, I'd be gong crazy/
Maybe just let it go and see? Maybe they like your emails and want to be within the inner circle, just not ready t make an investment yet. There are so many scenarios that could be played out here.
But you also do not need to reach out individually to everyone who doesn't sign up for anything, that may be too much. But that's juts me. If you have a super engaged list and this person is the only one not participating, and if you really feel like it, you could reach out to them.
But i just think that as our lists keep growing, we'd see more of this, and it may be bettre to start getting used to some of these peole.