Implement clear button for ion-select with a multiple values

I have a multiple select.
How I can implement the reset button for the select and show the blank value?

        <i class="fa fa-tags" aria-hidden="true"></i>{{'Categories' | translate}}</ion-label>
      <ion-select [(ngModel)]="categories" multiple="true" (ionCancel)="allClickedCategories()" [okText]="('Select' | translate)"
        [cancelText]="('Select All' | translate)" [selectOptions]="selectOptions">
        <ion-option *ngFor="let item of categoriesitems" value="{{}}">{{ | translate}}</ion-option>

      <ion-col col-6 class="center">
        <button ion-button (click)="buttonReset()">Reset</button>

      <ion-col col-6 class="center">
        <button ion-button (click)="buttonClicked()">{{'Search' | translate}}</button>

I try to implement the button reset with the code below: in the select i see the value but the array is empty


  buttonReset() {
    this.categories = [];

Thank You

just set [(ngModel)]=null in the function

  buttonReset() {
    this.categories = null;

I don’t delete the post because it can be useful to someone.