Try this

Sub Delete_Row_IfCellContainsCertainText()
    Dim Firstrow As Long
    Dim Lastrow As Long
    Dim Lrow As Long
    Dim CalcMode As Long
    Dim ViewMode As Long
    Dim ColumnLetter As String

    With Application
        CalcMode = .Calculation
        .Calculation = xlCalculationManual
        .ScreenUpdating = False
    End With
    With ActiveSheet
        .Select

        ViewMode = ActiveWindow.View
        ActiveWindow.View = xlNormalView
        .DisplayPageBreaks = False

        Firstrow = .UsedRange.Cells(1).Row
        Lastrow = .UsedRange.Rows(.UsedRange.Rows.Count).Row
        ColumnLetter = InputBox("What Column do you want to look in?")
        For Lrow = Lastrow To Firstrow Step -1
            With .Cells(Lrow, ColumnLetter)
                If Not IsError(.Value) Then
                    If .Value Like "*:*" Then .EntireRow.Delete
                End If
            End With
        Next Lrow
    End With