Ok, the plugin actually does not have a clear DB function as described in documentation (are you kidding?)
Anyway, there is a plug in called qTranslate X Cleanup and WPML Import, but clear this mode is temporary not supported and I’ve had some problem after installing it so I did not proceeded to clear with it.
I found a solution that worked here:
https://techjourney.net/fully-uninstall-remove-qtranslate-x-with-database-cleanup-of-unwanted-language-translations/
If you are not familiar with phpMyAdmin it can be a little scary but it doesn’t.
I’ve used the query described with qTrqnslateX 3.4.6.8 and WP 4.9.8.
After a DB backup I’ve tried the queryes once at time and notice if they really worked with a look at the table they pointed.
The queryes won’t clear everything but it’s a great time saving.
After running all queryes it’s a good idea to search the [:xx] tag inside the DB search field to find what it was not cleared by queryes and complete the work.
