如果在给定时间之前未单击激活链接，如何删除用户？

Question

我正在尝试在django应用中实现基于电子邮件验证的身份验证系统。我真正想要的是，电子邮件链接必须在一段时间后失效。即使用户单击它，该链接也不起作用，并且应该从数据库中删除该用户。该怎么做？

forms.py：

class UserForm(forms.ModelForm):
    password = forms.CharField(widget=forms.PasswordInput)

    class Meta:
        model = User
        fields = ['username', 'email', 'password',]

    def clean_email(self):
        email = self.cleaned_data['email']
        print('email cleaned data: ' + self.cleaned_data['email'])
        try:
            User.objects.get(email=email)
            raise forms.ValidationError('Email already exists.')
        except User.DoesNotExist:
            return email

views.py：

def register(request):
    form = UserForm(request.POST or None)
    if form.is_valid():
        user = form.save(commit=False)
        user.is_active = False
        # username = form.cleaned_data['username']
        # password = form.cleaned_data['password']
        # user.set_password(password)
        user.save()
    #     user = authenticate(username=username, password=password)
    #     if user is not None:
    #         if user.is_active:
    #             login(request, user)
    #             return render(request, 'set_goals/index.html')
    # context = {
    #     "form": form,
    # }
        current_site = get_current_site(request)
        mail_subject = 'Activate your blog account.'
        message = render_to_string('registration/acc_active_email.html', {
            'user': user,
            'domain': current_site.domain,
            'uid': urlsafe_base64_encode(force_bytes(user.pk)).decode(),
            'token': account_activation_token.make_token(user),
        })
        to_email = form.cleaned_data.get('email')
        email = EmailMessage(
            mail_subject, message, to=[to_email]
            )
        # email.send()
        user.email_user(mail_subject,message)
        return HttpResponse('Please confirm your email address to complete the registration')
    context = {
         "form": form,
        }
    return render(request, 'set_goals/register.html', context)
def activate(request, uidb64, token):
    try:
        uid = force_text(urlsafe_base64_decode(uidb64))
        user = User.objects.get(pk=uid)
    except(TypeError, ValueError, OverflowError, User.DoesNotExist):
        user = None
    if user is not None and account_activation_token.check_token(user, token):
        user.is_active = True
        user.save()
        login(request, user)
        # return redirect('home')
        return HttpResponse('Thank you for your email confirmation. Now you can login your account.')
    else:
        return HttpResponse('Activation link is invalid!')

如何使链接过期？或在给定时间后单击链接，如何从数据库中删除用户？请帮忙！