By calling the COOZ command you can select the objects you want to send to Z=0, you can also preselect them.

Send lines, polylines, blocks, texts, etc., to Z=0.

You can work with preselected objects or select the objects you want to flatten.

The installer that ran when you downloaded this app or plug-in from the Autodesk App Store will begin installing the app or plug-in. Alternatively, simply double-click the downloaded installer to install the app or plug-in. You may need to restart your Autodesk product to activate the app or plug-in. To uninstall this plug-in, exit your Autodesk product if you are currently running it, simply run the installer again, and select the "Uninstall" button. Alternatively, click Control Panel > Programs > Programs and Features (Windows 10/11) and uninstall it as you would any other app on your system.