I can't delete attachment files. The little X icon is disappear.

It is back after three hours. 

Hello luxe. I'm happy to learn you're now back on track with your work. In case you experience an issue with the site again in the future, I recommend clearing cache and cookies on your browser. Clearing cache and cookies helps fix most issues the browser may be having. Here's an article that shows you how to do this. You're more than welcome to reach back to me in the comments below if you need anything else. Otherwise, I wish you a great rest of the week. :)