Removing Identifiers from calibre library

I found an old post about this but the solution given did not work.
Then got to bottom of thread and found moderator say this was old post and things had changed. However, I did not find a new solution.
I have the same issue as the old post, many isbns, google, amazon and other stuff that need to be removed from a large amount of books. I am not very savy on the computer and could not understand the manual at all.
Any help would be greatly appreciated.:thanks: