#For SQL Server 2005, 2008, and 2008 R2 instances

#For SQL Server 2012 and newer instances

#If you can afford to take the SQL Server service down

#Security is not the main issue here

For SQL Server 2005, 2008, and 2008 R2 instances

For SQL Server 2012 and newer instances

If you can afford to take the SQL Server service down

Security is not the main issue here

Starting with SQL Server 2012, NT Authority\SYSTEM was no longer given rights to SQL Server by default. So another way to do that in these newer versions has been detailed by Argenis Fernandez:

There is also a function in dbatools.io, a Powershell solution for managing SQL Server, called Reset-SqlAdmin:

• https://dbatools.io/functions/other/reset-sqladmin/

Starting with SQL Server 2012, NT Authority\SYSTEM was no longer given rights to SQL Server by default. So another way to do that in these newer versions has been detailed by Argenis Fernandez:

There is also a function in dbatools.io, a Powershell solution for managing SQL Server, called Reset-DbaAdmin:

• https://dbatools.io/functions/other/reset-dbaadmin/

• How to add new sysadmin account when no sysadmin accounts exist

• How to add new sysadmin account when no sysadmin accounts exist