Unzip the downloaded release, and change the name of the folder to deleteinactiveusers.
In the ext directory of your phpBB board, create a new directory named dmzx (if it does not already exist).
Copy the deleteinactiveusers folder to /ext/dmzx/ (if done correctly, you'll have the main extension class at (your forum root)/ext/dmzx/deleteinactiveusers/composer.json).
Navigate in the ACP to Customise -> Manage extensions.
Look for Delete Inactive Users under the Disabled Extensions list, and click its Enable link.
Uninstall
Navigate in the ACP to Customise -> Extension Management -> Extensions.
Look for Delete Inactive Users under the Enabled Extensions list, and click its Disable link.
To permanently uninstall, click Delete Data and then delete the /ext/dmzx/deleteinactiveusers folder.
