Acrobate.exe not getting close (Killed)

Acrobat.exe not getting closed/ killed even after quitting the application.

Please find the code snippet below.

Public Sub Close()
Try
AcroPDFObj.gPDDOC.Close()
AcroPDFObj.gAVDOC.Close(False)
If Not AcroPDFObj.gApp Is Nothing Then
AcroPDFObj.gApp.Exit()
End If Catch ex As Exception
End Try
AcroPDFObj.gAVDOC = Nothing
AcroPDFObj.gPDDOC = Nothing
AcroPDFObj.gApp = Nothing
AcroPDFObj = Nothing

GC.Collect()
GC.WaitForPendingFinalizers()
End Sub

Please suggest what else needs to write to get Acrobat Process killed from task manager.