For a protected document using checkbox content controls as depicted in your sample, you would need code like:
Code:
Sub Demo()
Application.ScreenUpdating = False
Dim CCtrl As ContentControl, i As Long
Dim Pwd As String, pState As Variant
With ActiveDocument
If .ProtectionType <> wdNoProtection Then
Pwd = InputBox("Please enter the Password", "Password")
pState = .ProtectionType
.Unprotect Pwd
End If
With .Range
For i = .ContentControls.Count To 1 Step -1
With .ContentControls(i)
If .Type = wdContentControlCheckBox Then
If .Checked = False Then
With .Range.Rows(1)
.Range.Delete
.Delete
End With
End If
End If
End With
Next
End With
If pState <> wdNoProtection Then .Protect Type:=pState, NoReset:=True, Password:=Pwd
End With
Application.ScreenUpdating = True
End Sub