通常であれば下記で出来ると思いますが､

Option Explicit

Sub DeleteEmptyAreaSimple()
 Dim ws As Worksheet
 Dim lastRow As Long
 Dim lastCol As Long
 For Each ws In Worksheets
 With ws
 lastRow = ws.UsedRange.Rows.Count
 lastCol = ws.UsedRange.Columns.Count
 
 If lastCol < Columns.Count Then
 .Range(.Cells(1, lastCol + 1), .Cells(1, Columns.Count)).EntireColumn.Delete
 End If
 
 If lastRow < Rows.Count Then
 .Range(.Cells(lastRow + 1, "A"), .Cells(Rows.Count, "A")).EntireRow.Delete
 End If
 End With
 Next
End Sub

ｼｰﾄがﾃﾞｰﾀのない範囲まで､使用している範囲と認識していることも有るので､
実際のﾃﾞｰﾀを確認して範囲を削除する例です｡

Option Explicit

Sub DeleteEmptyArea()
 Dim ws As Worksheet
 For Each ws In Worksheets
 cleanupWS ws
 Next
End Sub

Sub cleanupWS(ws As Worksheet)
 Dim lastRow As Long
 Dim maxLastRow As Long
 Dim maxLastCol As Long
 
 With ws
 maxLastRow = .Cells(Rows.Count, "A").End(xlUp).Row
 maxLastCol = 1
 
 Dim c As Long
 For c = 2 To Columns.Count
 If Application.WorksheetFunction.CountA(.Columns(c)) <> 0 Then maxLastCol = c
 lastRow = .Cells(Rows.Count, c).End(xlUp).Row
 If lastRow > maxLastRow Then maxLastRow = lastRow
 Next
 
 If maxLastCol < Columns.Count Then
 .Range(.Cells(1, maxLastCol + 1), .Cells(1, Columns.Count)).EntireColumn.Delete
 End If
 
 If maxLastRow < Rows.Count Then
 .Range(.Cells(maxLastRow + 1, "A"), .Cells(Rows.Count, "A")).EntireRow.Delete
 End If
 End With
End Sub