This is similar to this question but with using database first entity framework instead of code first: How can I change the table names when using Visual Studio 2013 ASP.NET Identity?
In the code first approach you can override OnModelCreating and do something like this so that the user info is saved in MyUsers table instead of the default AspNetUsers:
modelBuilder.Entity<IdentityUser>().ToTable("MyUsers")
In the database first approach I have manually created the MyUsers table but because OnModelCreating does not get called I don't know how to configure the data to be saved into my new table?