I had to select in batches of 100-200 at a time, and it took over 5 hours to delete 10,000 files. I have never been so angry at a developer before this.
FYI there is another thread complaining about the deletion functionality, I hope that you will vote that one up.
The clear answer is not to use the adobe creative cloud for syncing. I have a few 1 gig files with a thousand edits. All end up in the trash and takes hours to delete.