Run below command to see a full list of enabled or disabled modules:
php bin/magento module:status
To enable a module, use the below command:
php bin/magento module:enable Magemonkeys_AjaxNewsletter
To disable a module use the below command:
php bin/magento module:disable Magemonkeys_AjaxNewsletter
To uninstall a module use the below command:
php bin/magento module:uninstall Magemonkeys_AjaxNewsletter