Brian Alexander

Adds the current page’s template name to the admin bar.
Because this plugin reveals potentially sensitive information about the active theme, it is recommended for development environments only, and should not be enabled on a production site.

What Template

Adds the current page's template name to the admin bar.

Scott Kingsley Clark

Pretty easy setup.. just install and activate it on the site of your choice (or network activate) and set up the settings however you’d like.
This plugin supports both Per-Site and Per-Network (WordPress Multisite) settings, so you can fine tune your options based on your needs.
Other plugins you might be interested in:
<ul>
<li>Showing the Admin Bar in more cases – <a href="https://wordpress.org/plugins/always-show-admin-bar/" rel="ugc">Always Show Admin Bar plugin</a></li>
<li>Showing the Admin Bar to logged out users – <a href="https://wordpress.org/plugins/logged-out-admin-bar/" rel="ugc">Logged Out Admin Bar plugin</a></li>
<li>Customizing the Admin area based on role – <a href="https://wordpress.org/plugins/adminimize/" rel="ugc">Adminimize</a></li>
</ul>

Admin Bar Disabler

Pretty easy setup.. just install and activate it on the site of your choice (or network activate) and set up the settings however you'd like.

What Template vs Admin Bar Disabler