How to change SQL Server Instance Name?

First collect the output of the current instance configuration

1. sp_helpserver
2. select @@servername

Execute the below query to change the instance name

1. sp_dropserver 'old_name'
2. go
3. sp_addserver 'new_name','local'
4. go
   

Verify sql server instance configuration by running below queries

1. sp_helpserver
2. select @@servername