First, you need to create at least two domain accounts, one as a farm account and one for other services!

• List all services and application pools that run with your current account.
• Create Domain Accounts in your AD.
• Add the newly created accounts to managed account.
• In SQL Server,
  • the new farm account should have db_creator and SecurityAdmin permission on the server level.
  • The service account should have an owner role on all database services.
• Open Configure service accounts in Central Administration and assign the new service account for the farm account application pool, services.

• Also, run the below cmdlet to update farm account credentials

  stsadm -o updatefarmcredentials -userlogin DomainName\UserName -password NewPassword
  

• Run iisreset /noforce to restart IIS

Actually, It's a risky process, so you should apply the above steps on a test environment, and next time you should follow SharePoint Service Accounts Best Practices

First, you need to create at least two domain accounts, one as a farm account and one for other services!

• List all services and application pools that run with your current account.
• Create Domain Accounts in your AD.
• Add the newly created accounts to managed account.
• In SQL Server,
  • the new farm account should have db_creator and SecurityAdmin permission on the server level.
  • The service account should have an owner role on all database services.
• Open Configure service accounts in Central Administration and assign the new service account for the farm account, application pool, services.

• Also, run the below cmdlet to update farm account credentials

  stsadm -o updatefarmcredentials -userlogin DomainName\UserName -password NewPassword
  

• Run iisreset /noforce to restart IIS

Actually, It's a risky process, so you should apply the above steps on a test environment, and next time you should follow SharePoint Service Accounts Best Practices