JeremyEnglert

Materiell

This plugin will display the currently activated theme name and version number in the admin toolbar. It is helpful for developers who are often switching between similar themes or versions of themes.

Theme Info in Toolbar

A plugin to display the theme name and version number in the admin toolbar area.

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.

Theme Info in Toolbar vs Admin Bar Disabler