Selecting Sheets Confirmation

I would like to use the below macro with other sheets in my workbook, how do i change the line "With Activesheet" to incorporate this? Lets say my other sheets are titled as: main, report, sheet3, sheet 4?

Sub Blanks()
Dim lastrow As Long, i As Long
Application.ScreenUpdating = False
Application.Calculation = xlManual
With ActiveSheet
lastrow = .Cells(Rows.Count, 3).End(xlUp).Row
For i = lastrow To 1 Step -1
If .Range("A" & i).Value = "" Then .Rows(i).Delete
Next i
End With
Application.ScreenUpdating = True
Application.Calculation = xlAutomatic
End Sub