You cannot edit an swf with Flash (or any other software I know of). You need to acquire the fla version of the file to make changes and publish a revised swf with it.
You might be able to use a decompiler to get an fla from the swf that you can edit, but you might also find that the file is an AS1/2 file in which case you won't be able to edit it with Flash CC.
Do you know any useful de compiler? Can I find out if the file is an AS1/2 before de complying it?
1 person found this helpful
I have no experience with any decompilers beyond possibly attempting to trial one once. The only one I have seen recommended is made by Sothink.
Here is a link to a page with a tool that has an interface you can use to determine various properties of an swf file, including the Actionscript version.