I checked but on the website it explicitely implies it doesn't remove the drm restrictions?
**Why does calibre not support DRM?
**
calibre is open source software while DRM by its very nature is closed. If calibre were to support opening or viewing DRM files it could be trivially modified to be used as a tool for DRM removal which is illegal under today’s laws. Open source software and DRM are a clash of principles. While DRM is all about controlling the user, open source software is about empowering the user. The two simply can not coexist.
Please be careful with your wording. Calibre does not remove DRM. Calibre does support plugins, and as it is a totally open source application, these plugins include third party ones for which the Calibre developers have no responsibility. One of these third party plugins will remove most types of ebook DRM.