Programatically create Partner Community Accounts using Apex / Salesforce

Step 1: GoTo Account Tab and Create a account name "User Account"
Step 2: On Account Details page click on button  "Manage External Account" and the click on "Enable As Partner". Make sure login user profile must have assign role

Then
user users=new users();
users.email='test@gmail.com';
users.firstname='ajay';

users.username='test@gmail.com';

users.lastname='Kumar';

 Id p = [select id from profile where name='Partner Community Profile'].id;
       account ac= [select id from account where name='User Account' limit 1 ];
       
       Contact objectContact = new Contact(LastName =users.lastname,AccountId = ac.Id);
       insert objectContact;
         
         User  u = new User(contactId=objectContact.Id,
                          username=users.username,
                          firstname=users.firstname,
                          lastname=users.lastname,
                          email=users.email ,
                          communityNickname = users.lastname.substring(0,1) + '_'+Math.random(),
                          alias = string.valueof(users.lastname.substring(0,1) +
                                  users.lastname.substring(0,1) + Math.random() ).substring(0,5),
                          profileid =p , emailencodingkey='UTF-8',
                          languagelocalekey='en_US',
                          localesidkey='en_US',
                          IsPrmSuperUser = true,

                          timezonesidkey='America/Los_Angeles');               
 
        insert u;