Whether installing or updating, whether this plugin or any other, it is always advisable to back-up your data before starting
Unzip restrict-usernames.zip inside the /wp-content/plugins/ directory for your site (or install via the built-in WordPress plugin installer)
Activate the plugin through the 'Plugins' admin menu in WordPress. In Multisite, Network Activate the plugin.
Go to the Users -> Name Restrictions admin settings page (which you can also get to via the Settings link next to the plugin on the Manage Plugins page) and specify username restrictions. On a Multisite install, go to My Sites -> Network Admin -> Users -> Name Restrictions.
Requires: 3.6 or higher Compatible up to: 4.2.2 Last Updated: 2015-4-17 Active Installs: