Cannot reset form - angularjs

Question

I'm new to Angular and I have a simple retrieve password form with 1 email field and a submit button. I want to clear the form after the form has been submitted, but I can't seem to do it even after following tutorials/answers online.
I think it might be something I'm not understanding fundamentally, so if you could please let me know that would be great.
I'm using Angular v1.2.22
HTML (signin.forgotpassword.html)
<form name="forgotPasswordForm" class="form" role="form" ng-submit="forgetPasswordSubmit(forgetForm.email)" novalidate >
<div>
<label for="input-email" class="col-sm-2 control-label">Email</label>
<div>
<input name="email" ng-model="forgetForm.email" type="email" class="form-control" id="input-email" />
</div>
</div>
<div class="form-group">
<div>
<button name="submit" type="submit">Reset Password</button>
</div>
</div>
</form>
Angular (AuthController)
var forgetPasswordClear = function(){
var defaultForm = {
email: ''
};
// clear input
$scope.forgetForm = defaultForm; // Doesn't clear
// set form as pristine
$scope.forgotPasswordForm.$setPristine(); // Get Cannot read property '$setPristine' of undefined
};
$scope.forgetPasswordSubmit = function(email){
forgetPasswordClear();
};
----------EDIT----------
I'm not sure if it's because my form is sitting in a different ui view? My structure looks something like this:
HTML
<section data-ng-controller="AuthController">
<div data-ui-view>
Some content in there originally
<a ui-sref="signin.forgetpassword">Click here to get password</a>
</div>
</section>
Ui router
.state('signin.forgotpassword', {
url: '/signup/forgot-password',
templateUrl: 'modules/core/templates/signin.forgotpassword.html'
})

Answer 1

You set the wrong model:
Your model is 'forgetForm'
<input name="email" ng-model="forgetForm.email" type="email" class="form-control" id="input-email" ng-pattern="/.+\#.+\..+/" autofocus required />
current:
$scope.forget = defaultForm;
should be:
$scope.forgetForm = defaultForm;
EDIT TO ADDRESS NEW PROBLEM
It's because this is a child scope.
You need to use event emitters and listeners.
$broadcast -- dispatches the event downwards to all child scopes,
$emit -- dispatches the event upwards through the scope hierarchy.
Read more here: Working with $scope.$emit and $scope.$on