VBA Help - Want to close one excel file but not the other without prompt to save

[MistakesWereMade]

My User Form opens another excel file. I want to close this newly opened file when I want, but not have excel ask me to close my User Form interface.

I have the below code in my ThisWorkbook VBA script window, but it still does not allow me to keep my User Form open after trying to close the other excel file.

Private Sub Workbook_Open()


    Application.Visible = False
    UserForm1.Show vbModeless
    
End Sub

I'd really appreciate some guidance.