Register users of different types using roles and polymorphism

In my laravel & vue.js app I need to have three types of users. Admin, Institution, User. I have created base table users and user_institution, user_personal using polymorphism. I have added Admin user with DatabaseSeeder and the admin should create institution users, and personal users need to register. I have roles table

public function up()
>     {
>         Schema::create('roles', function (Blueprint $table) {
>             $table->smallInteger('id')->primary()->unsigned();
> 
>             $table->string('name')->unique();
>             $table->string('display_name')->nullable();
>             $table->string('description')->nullable();
> 
>             $table->timestamps();
>         });
>     }
> 

Users Table

> public function up()
>     {
>         Schema::create('users', function (Blueprint $table) {
>             $table->bigIncrements('id');
>             $table->string('email')->unique();
>             $table->string('password');
> 
>             $table->string('avatar')->nullable();
> 
>             $table->morphs('userable');
>             $table->boolean('confirmed')->default(0);
>             $table->string('confirmation_code')->nullable();
>             $table->dateTime('confirmation_expiry')->nullable();
> 
>             $table->smallInteger('role_id')->unsigned();
>             $table->foreign('role_id')->references('id')->on('roles');
> 
>             $table->rememberToken();
>             $table->timestamps();
>         });
>     }

Models> RoleModel, UserModel, InstitutionModel, PersonalModel

How to create my api method for registering personal users and institution users. What i need for that?

via Chebli Mohamed