uninstall.php

<?php
if ( ! defined( 'WP_UNINSTALL_PLUGIN' ) ) {
	exit();
}

// Cleanup all data.
require 'core/wp-event-manager-data-cleaner.php';

if ( ! is_multisite() ) {

	// Only do deletion if the setting is true.
	$do_deletion = get_option( 'event_manager_delete_data_on_uninstall' );
	if ( $do_deletion ) {
		WP_Event_Manager_Data_Cleaner::cleanup_all();
	}
} else {
	global $wpdb;

	$blog_ids         = $wpdb->get_col( "SELECT blog_id FROM $wpdb->blogs" );
	$original_blog_id = get_current_blog_id();

	foreach ( $blog_ids as $blog_id ) {
		switch_to_blog( $blog_id );

		// Only do deletion if the setting is true.
		$do_deletion = get_option( 'event_manager_delete_data_on_uninstall' );
		if ( $do_deletion ) {
			WP_Event_Manager_Data_Cleaner::cleanup_all();
		}
	}

	switch_to_blog( $original_blog_id );
}

$options = array(
		'event_manager_enqueue_boostrap_frontend',
		'event_manager_enqueue_boostrap_backend',
		'event_manager_delete_data_on_uninstall',
		'event_manager_google_maps_api_key',
		'event_manager_per_page',
		'event_manager_hide_cancelled_events',
		'event_manager_hide_expired',
		'event_manager_hide_expired_content',
		'event_manager_enable_categories',
		'event_manager_enable_event_types',
		'event_manager_enable_event_ticket_prices',
		'event_manager_enable_default_category_multiselect',
		'event_manager_enable_default_event_type_multiselect',
		'event_manager_category_filter_type',
		'event_manager_event_type_filter_type',
		'event_manager_user_requires_account',
		'event_manager_enable_registration',
		'event_manager_generate_username_from_email',
		'event_manager_use_standard_password_setup_email',
		'event_manager_registration_role',
		'event_manager_submission_requires_approval',
		'event_manager_user_can_edit_pending_submissions',
		'event_manager_user_can_add_multiple_banner',
		'event_manager_delete_expired_events',
		'event_manager_submission_expire_options',
		'event_manager_submission_duration',
		'event_manager_allowed_registration_method',
		'event_manager_multiselect_event_type',
		'event_manager_multiselect_event_category',
		'event_manager_time_format',
		'event_manager_submit_event_form_page_id',
		'event_manager_event_dashboard_page_id',
		'event_manager_events_page_id',

		'enable_event_organizer',
		'enable_event_venue',
		'event_manager_date_time_format_separator',
		'event_manager_datepicker_format',
		'event_manager_delete_events_after_finished',
		'event_manager_form_fields',
		'event_manager_installed_terms',
		'event_manager_login_page_url',
		'event_manager_organizer_dashboard_page_id',
		'event_manager_paid_listings_flow',
		'event_manager_rating_showcase_admin_notices_dismiss',
		'event_manager_submit_event_form_fields',
		'event_manager_submit_organizer_form_fields',
		'event_manager_submit_organizer_form_page_id',
		'event_manager_submit_venue_form_fields',
		'event_manager_submit_venue_form_page_id',
		'event_manager_timepicker_format',
		'event_manager_timepicker_step',
		'event_manager_timezone_setting',
		'event_manager_venue_dashboard_page_id',
		'event_manager_event_venues_page_id',
		'event_manager_view_date_format',
		'wp_event_manager_version',
		'wpem_permalinks',
		'event_manager_upgrade_database',
		'wp_event_manager_db_version',
		'wpem_installation',
		'wpem_installation_skip',
);

foreach ( $options as $option ) {
	delete_option( $option );
}