Django deleting default form labels

While styling Authentication form i got defining labes "Username" and "Password" picture is here. How to delete these elements?

Forms module

class LogForm(AuthenticationForm):
username = forms.CharField(widget=forms.TextInput(attrs={'class': 'form-control', 'placeholder': 'Enter Login'}))
password = forms.CharField(widget=forms.PasswordInput(attrs={'class': 'form-control', 'placeholder': 'Enter Login'}))