Console/Command/EnableCommand.php
private function disableFastly()
    {
        $this->configWriter->save(
            'system/full_page_cache/caching_application',
            \Magento\PageCache\Model\Config::BUILT_IN
        );
        $this->output->writeln(
            '<info>Fastly Caching Application Deactivated, default built in Caching mechanism set.</info>',
            OutputInterface::OUTPUT_NORMAL
        );
    }
private function disableFastly()
    {
        $this->configWriter->save(
            'system/full_page_cache/caching_application',
            \Magento\PageCache\Model\Config::BUILT_IN
        );
        $this->output->writeln(
            '<info>Fastly Caching Application Deactivated, default built in Caching mechanism set.</info>',
            OutputInterface::OUTPUT_NORMAL
        );
    }
Disable Fastly