What do you mean by user? The ANSI_PADDING setting is one of the connection string settings and with SSMS and ADO.NET it defaults to ON. In SSMS you can make a global change through Tools->Options->Query Execution->SQL Server->ANSI or by individual query session under Query->Query Options->Execution-ANSI. OR you can just do SET ANSI_PADDING ON/OFF statement.

Using ADO.NET you need to execute a SET ANSI_PADDING OFF as part of the application.