Drop failed for User 'VRN\kaluk'. (Microsoft.SqlServer.Smo)

How do you drop this user, 'VRN\kaluk'?

Error list below:



Drop failed for User 'VRN\kaluk'.  (Microsoft.SqlServer.Smo)

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For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.3042.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Drop+User&LinkId=20476

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Program Location:

   at Microsoft.SqlServer.Management.Smo.SqlSmoObject.DropImpl()
   at Microsoft.SqlServer.Management.Smo.User.Drop()
   at Microsoft.SqlServer.Management.SqlManagerUI.DropObjects.DoDropObject(Int32 objectRowIndex)
   at Microsoft.SqlServer.Management.SqlManagerUI.DropObjects.DropAllObjects(Boolean stopOnError)

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TITLE: Microsoft SQL Server Management Studio
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Drop failed for User 'VRN\kaluk'.  (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.3042.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Drop+User&LinkId=20476

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ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

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The database principal owns an assembly and cannot be dropped. (Microsoft SQL Server, Error: 15154)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=09.00.3068&EvtSrc=MSSQLServer&EvtID=15154&LinkId=20476

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BUTTONS:

OK
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An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

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Program Location:

   at Microsoft.SqlServer.Management.Common.ServerConnection.ExecuteNonQuery(String sqlCommand, ExecutionTypes executionType)
   at Microsoft.SqlServer.Management.Common.ServerConnection.ExecuteNonQuery(StringCollection sqlCommands, ExecutionTypes executionType)
   at Microsoft.SqlServer.Management.Smo.ExecutionManager.ExecuteNonQuery(StringCollection queries)
   at Microsoft.SqlServer.Management.Smo.SqlSmoObject.ExecuteNonQuery(StringCollection queries, Boolean includeDbContext)
   at Microsoft.SqlServer.Management.Smo.SqlSmoObject.DropImplWorker(Urn& urn)
   at Microsoft.SqlServer.Management.Smo.SqlSmoObject.DropImpl()

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The database principal owns an assembly and cannot be dropped. (.Net SqlClient Data Provider)

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For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=09.00.3068&EvtSrc=MSSQLServer&EvtID=15154&LinkId=20476

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Server Name: dv01
Error Number: 15154
Severity: 16
State: 1
Line Number: 2


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Program Location:

   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at Microsoft.SqlServer.Management.Common.ServerConnection.ExecuteNonQuery(String sqlCommand, ExecutionTypes executionType)