What's the best way to add a default admin user in NodeJS/MongoDB app?

So I have an application developed in NodeJS, which is using the MongoDB for database (with Mongoose). Besides the application, there is an admin panel where administrators can manage all the data being added by regular users.

In the users schema, I have the following prop:

role: {
    type: String,
    default: "user",
    enum: ["user", "admin"]
},

My question is, what's the best/secure way to add one or two admin users?