Reset the ion-option values on (ionChange) - ionic 2 - asp.net

Question

Does anyone know how to reset the "ion-option" values of "ion-select". I have two ion-select controls and i want my first ion-select(selectedPLocation) to change the values of my 2nd ion-select(selectedLocation) on ionChange. I am able to remove selected by setting null but i am not able to change the values of selectedLocation. Does anyone know how to reset the value of my ion-options ?
I'm currently using VS2015 s my IDE.
HTML:
<ion-list>
<ion-item>
<ion-label>Parent Location</ion-label>
<ion-select [(ngModel)]="selectedPLocation" (ionChange)="loadLocation()">
<ion-option *ngFor="let parentLocation of parentLocations; let i=index" [value]="parentLocation.Key">{{parentLocation.Id}}</ion-option>
</ion-select>
</ion-item>
<ion-item>
<ion-label>Location</ion-label>
<ion-select [(ngModel)]="selectedLocation">
<ion-option id="locationID" *ngFor="let location of locations; let i=index" [value]="location.Key">{{location.Id}}</ion-option>
</ion-select>
</ion-item>
</ion-list>
TypeScript:
public loadLocation() {
let loader = this.loadingCtrl.create({
content: "Please wait..."
});
loader.present();
this.selectedLocation = null; //Reset selected value only
this.locations = null; //Tried this but can't seem to reset the values
this.locationService.GetLocations(this.global.getApiUrl(), this.selectedSite, this.selectedPLocation).then(data => {
loader.dismiss();
this.locations = data;
}).catch((err) => {
loader.dismiss();
let alert = this.alertCtrl.create({
title: 'Error',
subTitle: err,
buttons: ['OK']
});
alert.present();
});}

Answer 1

I solved my own error, it is due to my Typescript codes call to my web service API (GetLocation).
Previous TypeScript Code:
public GetLocations(apiUrl, siteKey, pLocationKey) {
return new Promise((resolve, reject) => {
this.http.get(apiUrl + "site/" + siteKey + "/location/" + pLocationKey)
.map(res => res.json())
.subscribe(data => {
this.Locations = data; //Error Here
resolve(this.Locations);; //Error Here
},
err => {
reject(err);
});
});
}
Correct TypeScript Code:
public GetLocations(apiUrl, siteKey, pLocationKey){
return new Promise((resolve, reject) => {
this.http.get(apiUrl + "site/" + siteKey + "/location/" + pLocationKey)
.map(res => res.json())
.subscribe(data => {
resolve(data); //Corrected
},
err =>{
reject(err);
});
});
}