safety uninstall metatags_quick
1. Delete the fields:
drush ev "field_delete_field('meta_canonical'); field_delete_field('meta_description'); field_delete_field('meta_keywords');"
2. Run cron to actually delete the data and fields
drush cron && drush cron
If there are lots of entries you need to run cron more often or purge the data manually by calling drush ev "field_purge_batch(5000)"; see also http://drupal.stackexchange.com/questions/38328/clean-deleted-field-from....
3. You should now be able to uninstall the module :
drush dis metatags_quick && drush pm-uninstall metatags_quick