Remove Tags on Pocketbook Touc Lux 4

Hello,

first of all, sorry if there is already a similar question answered- I could't seem to find it.

I have worked diligently labeling all my calibre library books in a "genre" column. I made my own classification.

Now I deleted all tags on my portable calibre (clicking in the bulk metedata windo, remove all tags). But when I send my clean of tags books to Pocketbook Touch Lux 4, they still show there in the genre section.

How can I remove them from showing on my device? or maybe I didn't succesfully delete them from calibre itself? If no, then how to do that?

My calibre version is 3.12

Thanks in advance!