You can use import records to import a table from your all in one file into your new file. THen use Manage | External Sources to establish a link to the new file. Open Manage | Database | Relationships to update any table occurrences to point to the new external table in place of the internal table.
Any Accounts/Privileges will have to be created step by step in your new file to match those in the original.
is it possible to change the different tables into files
You can duplicate the file several times, change the references and delete what you don't need. But why would you want to do such a thing?
Interesting . . . the one solution (major, probably only to me) I've developed consists of seven files plus a Help file. I'm seeing compelling reasons to do exactly the opposite of what you propose. As far as I know, the reasons for using separate files become fewer as time goes on. For example, I don't think there's a limit of 100 custom menu items anymore in version 10 (someone correct me if I'm wrong). As well, making any major relational change in a file can mean reflecting this change in every other file using an occurrence of the table in the original file. Even after a few years I've surprised myself by forgetting this, and had a layout filled with "?". I agree with many of the other posters. If it isn't necessary don't do it.