Your Blog theme can be identified easily by checking the page source and searching for the term “themes”. If you have to hide the theme name all you need to do is rename the theme folder from the FTP of your web hosting. But if you are renaming an active theme on your blog, it will cause several working issues and hence you will have to change the theme to the default one and then rename the intended theme folder.
You might be skeptical to change the folder name worrying if the structure or theme performance might be affected but if the folder name is changed when the theme is not in use, it should not be a problem at all. After changing the theme, you can rebuilding the permalink structure even though its not a must.
PS: To rebuild the permalink structure, go to settings -> permalinks -> save. Hope this simple tutorial has helped you change the name of the targeted theme.