Hello Gaytri,
If this workbook is send by another user,Make sure that Inventory sheet is hide or strictly hide.
I guess that you got a workbook where Inventory sheet Marked Hidden.Please let me know after Verification.
Your second answer,Off course you can delete many unnecessary sheets while keeping some in your Workbook.
Try this code.
Sub DelAllNotMain()
Dim Wrksht As Worksheet
Application.DisplayAlerts = False
Application.ScreenUpdating = False
For Each Wrksht In Worksheets
If Wrksht.Name <> "Master" And Wrksht.Name <> "Main" And Wrksht.Name <> "Inventory" Then Wrksht.Delete
Next
Application.ScreenUpdating = True
End Sub