Ghost-Admin/app/components/modal-delete-theme.hbs

<header class="modal-header" data-test-delete-theme-modal>
    <h1>Are you sure you want to delete this</h1>
</header>
<a class="close" href="" role="button" title="Close" {{action "closeModal"}}>{{svg-jar "close"}}<span class="hidden">Close</span></a>

<div class="modal-body">
    <p>You're about to delete "<strong>{{this.theme.label}}</strong>". This is permanent! We warned you, k? Maybe <a href="#" {{action this.download}}>Download your theme before continuing</a></p>
</div>

<div class="modal-footer">
    <button {{action "closeModal"}} class="gh-btn" data-test-cancel-button><span>Cancel</span></button>
    <GhTaskButton @buttonText="Delete" @successText="Deleted" @task={{this.deleteTheme}} @class="gh-btn gh-btn-red gh-btn-icon" data-test-delete-button="true" />
</div>