Just nitpicking, but an admin account is one that has wide control over the PC, which is something you don't look like you're after. What you're looking for is a "Standard" user account in Windows.
However the problem I'm seeing is the original account on the PC also is shared on the Xbox. Since that PC is now tied to the account, I don't think Windows will let you reduce the account privileges on the PC to a standard account. And while you can log in Windows store apps with the Microsoft account on a local Standard user account, if the password is the same as the account that can do anything, what's the point? Although that's me assuming the password is known.
You're going to have to make a new Microsoft account, disassociate the PC with the original account, and re-register the PC to the new one. This way, this new account is the admin account on the PC and the account the others have access to can be a Standard user.
So yes, it's doable, you just have to jump through some hoops to get what you want.