1. Open any Figma file.
2. Click on the Actions icon in the bottom Figma toolbar.
3. Click the Plugins & Widgets tab to filter results to Figma plugins.
4. Search for {plugin} in the search bar.
5. Click on the {plugin} search result.
6. Click the Remove button to uninstall the {plugin} plugin.

This will remove the plugin from your Saved Plugins list, however, the Figma plugin may still show up under your Recents list (if it has been recently run), as Figma saves this list of recent plugins in your browser's/app's local storage. The plugin will vanish from the Recents menu after other plugins are run to take its place.