Clear / clean thumbnails in my site

-- HikaShop version -- : 2.3.4
-- Joomla version -- : 3.3.6

My client is never deleting one single product, he always unpublishes old products but for his working scheme can not delete them.

So all images for each product stay stored forever.

I wonder if, to clean the whole site a little and free some disk space I could make a massive deletion of all the 'thumbnail' named folders inside media/upload/ so I clear a lot of outdated and not used anymore images despite I understand the system will create again the already usable ones.

Is this the right behaviour og HikaShop? Will it rebuild the thumbnails starting from original uploaded photos?

P.D.: I know that in HikaShop 2.3.5 the images folder hac changed to root/images... but this is not the topic, I understand this would be the same in both cases before and after 2.3.5