Delete Rows that contain matching cell contents in column to the contents in cell B1

Try this little change

Sub DeleteMatchingRows()
    Dim LR As Long, I As Long
    With Sheets("Tracker")
        LR = .Range("B" & Rows.Count).End(xlUp).Row
        For I = LR To 2 Step -1
            If .Range("B" & I).Value = ActiveCell.Value Then .Rows(I).Delete
        Next I
    End With
End Sub