To obtain copies of these REXX files, what you'll need to do is open the Edit Rexx settings dialog and note the file names and paths.
You can find these files in one or two places: %AP_SITE%\My Files\Rexx OR %AP_HOME%\Distrib. Open Windows Explorer and point it to these paths explicitly and you will find all of your REXX files in one or both of these locations.
If you plan to move the REXX files to another AP server, then you should copy and paste the files into the folders of the same name where they were found because the location of these files mean something in Automation Point. If you find a file with the same filename in both locations, then (1) copy the file from your Distrib directory into the Distrib directory on your new server, and (2) copy the file from your MyFiles\Rexx into the MyFiles\Rexx folder on the new AP server. This is important because the MyFiles\Rexx file overrides the file with the same name in the Distrib folder, which may be an original version of this rexx distributed with the product, so you'll want to keep that there.