We wouldn’t be following our own advice without having a clean uninstall option.
Perform a clean uninstall of Perfmatters
When enabled, this will cause all Perfmatters options data to be removed from your database when the plugin is uninstalled. It will also remove any files or folder directories, such as MU and local Google Fonts. Follow the steps below.
Click into the Perfmatters plugin settings.
Under the “Tools” tab, make sure you have the “Plugin” sub-navigation menu selected.
Enable the “Clean Uninstall” option.
Scroll down and click “Save Changes.”
Click into “Plugins → Installed Plugins.”
Deactivate the Perfmatters plugin and then click “Delete.” All the database options, directories, files, settings, etc. will then be removed.