Uninstall an Existing Instance of SQL Server (Setup)
This article describes how to uninstall a stand-alone instance of SQL Server. By following the steps in this article, you also prepare the system so that you can reinstall SQL Server.
To uninstall an instance of SQL Server, you must be a local administrator with permission to log on as a service.
To uninstall a SQL Server failover cluster, use the Remove Node functionality provided by SQL Server Setup to remove each node individually. For more information, see Add or Remove Nodes in a SQL Server Failover Cluster (Setup)
Note the following important scenarios before you uninstall SQL Server:
Before you remove SQL Server components from a computer that has the minimum required amount of physical memory, make sure that the page file size is sufficient. The page file size must be equal to two times the amount of physical memory. Insufficient virtual memory can cause an incomplete removal of SQL Server.
If you have multiple instances of SQL Server, the SQL Server Browser uninstalls automatically when the last instance of SQL Server 2017 is uninstalled.
If you want to uninstall all components of SQL Server 2017, you must uninstall the SQL Server Browser component manually from Programs and Features in Control Panel.
- Uninstalling SQL Server deletes tempdb data files that were added during the install process. Files with tempdb_mssql_*.ndf name pattern are deleted if they exist in the system database directory.
Before You Uninstall
Back up your data. Although this is not a required step, you might have databases that you want to save in their present state. You might also want to save changes that were made to the system databases. If either situation is true, make sure that back up the data before you uninstall SQL Server. Alternatively, save a copy of all the data and log files in a folder other than the MSSQL folder. The MSSQL folder is deleted during uninstallation.
The files that you must save include the following database files:
ReportServer[$InstanceName] This is the Reporting Services default database.
ReportServer[$InstanceName]TempDB This is the Reporting Services default temporary database.
Delete the local security groups. Before you uninstall SQL Server, delete the local security groups for SQL Server components.
Stop all SQL Server services. We recommend that you stop all SQL Server services before you uninstall SQL Server components. Active connections can prevent successful uninstallation.
Use an account that has the appropriate permissions. Log on to the server by using the SQL Server service account or by using an account that has equivalent permissions. For example, you can log on to the server by using an account that is a member of the local Administrators group.
To Uninstall an Instance of SQL Server
To begin the uninstall process, go to Control Panel and then Programs and Features.
Right click SQL Server 2016 and select Uninstall. Then click Remove. This starts the SQL Server Installation Wizard.
Setup Support Rules runs to verify your computer configuration. To continue, click Next.
On the Select Instance page, use the drop-down box to specify an instance of SQL Server to remove, or specify the option to remove only the SQL Server shared features and management tools. To continue, click Next.
On the Select Features page, specify the features to remove from the specified instance of SQL Server.
Removal rules runs to verify that the operation can complete successfully.
On the Ready to Remove page, review the list of components and features that will be uninstalled. Click Remove to begin uninstalling
Immediately after you uninstall the last SQL Server instance, the other programs associated with SQL Server will still be visible in the list of programs in Programs and Features. However, if you close Programs and Features, the next time you open Programs and Features, it will refresh the list of programs, to show only the ones that are actually still installed.
If the Uninstallation Fails
If the uninstallation process does not complete successfully, attempt to fix the problem that caused the uninstallation to fail. The following articles can help you understand the cause of the failed uninstallation:
If you are unable to fix the cause of the uninstallation failure, you can contact Microsoft Support. In some cases, such as unintentional deletion of important files, reinstalling the operating system may be required before reinstalling SQL Server on the computer.
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