https://www.cnblogs.com/grisa/p/10369295.html
https://www.jb51.net/article/137030.htm
One: Open the Uninstaller
Select Delete
appear
4) Click OK - the following screen - select Delete the default instance (MSSQLSERVER) - Next
5) Select function (check all) - the next step execution
6) Delete Rule (default) - the next step execution
7) prepare to enter delete interface - check the installation path - delete
8) Delete complete - view the status of deleted
9) enter the installation path disk, it will delete the folder (to the c: \ program Files and program Files (x86) on microsoft SQL sever the relevant folder deletion)
10) into the registry
1, the HKEY_CURRENT_USER-Software - Microsoft SQL Server at Microsoft folder Delete all
2, 2012 Redist Microsoft SQL Native Client in HKEY_LOCAL_mACHINE-SOFTWARE-Microsoft, Microsoft SQL Server, Microsoft SQL Server Delete all
Note: There may be more than this several, spotted delete all on the line
