You should be able to deselect the only user pod in the desktop user manager.

chrome/browser/resources/login/user_pod_row.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview User pod row implementation.
  */
 
 cr.define('login', function() {
   /**
@@ skipping 1364 matching lines @@
 
     /**
      * Returns all the pods in this pod row.
      * @type {NodeList}
      */
     get pods() {
       return Array.prototype.slice.call(this.children);
     },
 
     /**
-     * Return true if user pod row has only single user pod in it.
+     * Return true if user pod row has only single user pod in it, which should
+     * always be focused.
      * @type {boolean}
      */
-    get isSinglePod() {
-      return this.children.length == 1;
+    get alwaysFocusSinglePod() {
+      var isDesktopUserManager = Oobe.getInstance().displayType ==
+          DISPLAY_TYPE.DESKTOP_USER_MANAGER;
+
+      return isDesktopUserManager ? false : this.children.length == 1;
     },
 
     /**
      * Returns pod with the given app id.
      * @param {!string} app_id Application id to be matched.
      * @return {Object} Pod with the given app id. null if pod hasn't been
      *     found.
      */
     getPodWithAppId_: function(app_id) {
       for (var i = 0, pod; pod = this.pods[i]; ++i) {
@@ skipping 199 matching lines @@
       // Desktop: recalculate pods layout right away.
       if (isDesktopUserManager || isCrosAccountPicker) {
         this.placePods_();
 
         // Without timeout changes in pods positions will be animated even
         // though it happened when 'flying-pods' class was disabled.
         setTimeout(function() {
           Oobe.getInstance().toggleClass('flying-pods', true);
         }, 0);
 
-        this.focusPod(this.preselectedPod);
+        // On desktop, don't pre-select a pod if it's the only one.
+        if (isDesktopUserManager && this.pods.length == 1)
+          this.focusPod();
+        else
+          this.focusPod(this.preselectedPod);
       } else {
         this.podPlacementPostponed_ = true;
 
         // Update [Cancel] button state.
         if ($('login-header-bar').signinUIState ==
                 SIGNIN_UI_STATE.GAIA_SIGNIN &&
             emptyPodRow &&
             this.pods.length > 0) {
           login.GaiaSigninScreen.updateCancelButtonState();
         }
@@ skipping 246 matching lines @@
       }
 
       // Make sure there's only one focusPod operation happening at a time.
       if (this.insideFocusPod_) {
         this.keyboardActivated_ = false;
         return;
       }
       this.insideFocusPod_ = true;
 
       for (var i = 0, pod; pod = this.pods[i]; ++i) {
-        if (!this.isSinglePod) {
+        if (!this.alwaysFocusSinglePod) {
           pod.isActionBoxMenuActive = false;
         }
         if (pod != podToFocus) {
           pod.isActionBoxMenuHovered = false;
           pod.classList.remove('focused');
           pod.classList.remove('faded');
           pod.reset(false);
         }
       }
 
@@ skipping 138 matching lines @@
       // Clear all menus if the click is outside pod menu and its
       // button area.
       if (!findAncestorByClass(e.target, 'action-box-menu') &&
           !findAncestorByClass(e.target, 'action-box-area')) {
         for (var i = 0, pod; pod = this.pods[i]; ++i)
           pod.isActionBoxMenuActive = false;
       }
 
       // Clears focus if not clicked on a pod and if there's more than one pod.
       var pod = findAncestorByClass(e.target, 'pod');
-      if ((!pod || pod.parentNode != this) && !this.isSinglePod) {
+      if ((!pod || pod.parentNode != this) && !this.alwaysFocusSinglePod) {
         this.focusPod();
       }
 
       if (pod)
         pod.isActionBoxMenuHovered = true;
 
       // Return focus back to single pod.
-      if (this.isSinglePod) {
+      if (this.alwaysFocusSinglePod) {
         this.focusPod(this.focusedPod_, true /* force */);
         if (!pod)
           this.focusedPod_.isActionBoxMenuHovered = false;
       }
     },
 
     /**
      * Handler of mouse move event.
      * @param {Event} e Click Event object.
      * @private
@@ skipping 48 matching lines @@
           e.target.focus();
         }
         return;
       }
 
       // Clears pod focus when we reach here. It means new focus is neither
       // on a pod nor on a button/input for a pod.
       // Do not "defocus" user pod when it is a single pod.
       // That means that 'focused' class will not be removed and
       // input field/button will always be visible.
-      if (!this.isSinglePod)
+      if (!this.alwaysFocusSinglePod)
         this.focusPod();
     },
 
     /**
      * Handler of keydown event.
      * @param {Event} e KeyDown Event object.
      */
     handleKeyDown: function(e) {
       if (this.disabled)
         return;
@@ skipping 27 matching lines @@
             if (e.target == this.focusedPod_.passwordElement ||
                 (targetTag != 'INPUT' &&
                  targetTag != 'BUTTON' &&
                  targetTag != 'A')) {
               this.setActivatedPod(this.focusedPod_, e);
               e.stopPropagation();
             }
           }
           break;
         case 'U+001B':  // Esc
-          if (!this.isSinglePod)
+          if (!this.alwaysFocusSinglePod)
             this.focusPod();
           break;
       }
     },
 
     /**
      * Called right after the pod row is shown.
      */
     handleAfterShow: function() {
       // Without timeout changes in pods positions will be animated even though
@@ skipping 59 matching lines @@
       if (this.podsWithPendingImages_.length == 0) {
         this.classList.remove('images-loading');
       }
     }
   };
 
   return {
     PodRow: PodRow
   };
 });