ADE do NOT delete eBooks

Hi, use ADE v4.5.1.139278 on an Windows 10 DELL Laptop. All updates incl. Norton Security.

Read an DRM-PDF File "c't Android 2016" wich is loaded today with expired date 6 Days more.

After reading I delete that Book with "Aus Bibliothek entfernen" (remove from bibliothek).

This will be done BUT after close the ADE-App and start this agian the Book "c't Android 2016" is loaded thru the internet-connetction from whatever.

This loading neads about 20-40 seconds. This feature does not happen when the internet-connection is broken.

Asking Adobe to help me find the right product (from adobe) to see my cloude-memory. Answer is that the product ADE does not synchronize any files.

So my question is: HOW to delete "Books" from the adobe digital editions?

Thank You and sorry my rosty english

Fred from Berlin