Sub deleteblank Dim book_sht As Worksheet
Dim sht_Rng As Range
Dim i, data_rows

Set book_sht = Worksheets(1)
Set sht_Rng = book_sht.UsedRange
data_rows = sht_Rng.Rows(sht_Rng.Rows.Count).Row

For i = 1 To data_rows
ActiveCell.Value = Application.WorksheetFunction.Substitute(Trim(ActiveCell.Value), " ", "")
ActiveCell.Offset(1, 0).Select

Set sht_Rng = Nothing
Set book_sht = Nothing

End Sub

I have the above VBA code that helps to clear one column of cell.
How can I modify it so that the code can help me to look through all column?