Anytime I talk to designers about what it means to be a manager, there's always a lot of concern over two things: what it means to stop doing hands-on work and how it's possible to force yourself to let go of that control. The prospect of not getting to design full-time is scary enough, to be sure. Add to that the potential randomness of someone else doing the work and it's easy to understand why moving toward a management role can be intimidating and honestly pretty hive-inducing for designers (or anyone, really). Getting through that feeling required a few realizations that hopefully can help speed up your own transition.
There are much, much better designers than you out there.
I consider myself lucky in that, not having a formal design education, I kind of always knew this one. And lucky for you, most designers have imposter syndrome, so you probably suspect this as well. Wonder no more: there are absolutely designers who are much, much more talented than you are. Some may be killing it right now. Others may have raw talent, but need some guidance and support to realize their full potential (that's where you come in!). But they're out there. Hire them.
Talent isn't enough. Hire people who believe in the vision.
Okay, don't just hire anyone with talent. If there's anything I've learned time and again, it's that talent just isn't enough. I've met incredibly talented people (like, on-a-rocketship-holy-crap-we're-moving-so-fast talented) who weren't great fits for the job because they didn't have the same vision as the rest of the team. This usually manifests as a candidate having specific, personal goals for the company ("I want to redesign the site", "I want to rewrite this crappy CSS", etc.) as opposed to asking about the goals of the company (the "why we're doing all these things" part) and placing themselves within that context in the most effective way.
There are a lot of different layers of vision within a company as well. Take BuzzFeed for instance: there's the vision of the entire organization. There's vision for the Product Development team's growth and evolution. There's a vision for the Design team. Each smaller context should support and plug into the larger ones. If you're on a team with no vision, take some time to come up with one. It'll help you identify not only what you believe, but who out there believes in what you believe in.
And hiring people who believe in the vision is absolutely essential for letting go of the reins as a manager. If you haven't read Simon Sinek's Start With Why, you absolutely should. When you hire people who understand and are enthusiastic about the vision, you can trust that they'll make choices that move everyone (and the company) forward as opposed to choices that move only themselves forward.
Trust is essential. This doesn't make it easy.
If you've hired a team that believes in the same vision and is working toward that, it definitely becomes much easier to trust them and let go of the day-to-day work. However, just because it's easier, doesn't mean it's easy. Trust is hard and something I struggle with every single day. The most difficult part about design work particularly is that there's usually such a wide delta between the first iteration and the thing you ship. It takes a ton of restraint to allow people to explore on their own, and it's a very fine line between guiding designers and directing every decision.
What's worked for me so far is to become partners and collaborators with the people I manage. I've heard this advice that managers shouldn't be friends with the people they manage. While there's certainly some truth to that (though I believe there's less than most people think), a lot of managers make the mistake of taking that advice so literally that they avoid partnering closely with their team members. As a manager, you and your team should be in this together. If you're checking in and helping brainstorm and unstick the designers you work with regularly, trust is an inevitable byproduct. Think about it: who have you trusted the most in your career to make good decisions (even as a designer)? The people you collaborated with every single day? Or the folks who appeared at various points during your process to give feedback and then move on until the next time (we call this the "swoop and poop")?
Letting go isn't really letting go.
Maybe you're starting to get the impression that letting go isn't really a thing. I didn't realize until I wrote all this down that it probably isn't and should never be. Sure, you have to let go of the physical act of opening Sketch and designing things. You may never open a code editor. But trusting people means building trust with them. Which means working closely together to make great things. Honestly, if there's one thing I'd say to more managers it's this: get involved. Make great hires, trust the team you've got and become their greatest cheerleader and collaborator. With any luck, you too will come to realize how satisfying and fulfilling the move to management can be.