I tried looking for info about the plugin probably not working under v6.x of Calibre but honestly I'm a bit lost. I saw mentions of a DeDRM 10.0.3 and from there I'm confused heh So is there a working plugin for v6.x or I better downgrade to 5.44 for now?
Edit : Okay, so I finally figured it out, here's how :
Went there to download the 10.0.3 zip file :
https://github.com/noDRM/DeDRM_tools/releases
Unzipped and then added both DeDrm and Obok plugins in Calibre... NOW it works!!