Unfortunately, Apple does not make this easy. When you are viewing an album, you are viewing a collection of “Assets.” RAW+JPEG is represented in the photo database as a single “asset”. Apple does not provide a way for third parties to split apart an asset, while retaining the metadata etc. associated. Nor do they provide a way to delete parts of an asset.
With a fair amount of work, it might be possible to write some code that examines the asset in detail, downloads all of the pieces, and creates a new asset that has just the RAW or just the JPEG, along with any adjustments or other data. However, it’s not clear if keywords or place information etc. will also travel along with it. Assuming it could be done, the new asset would be created, and the old paired asset would be deleted.
Anyway, I have been asked for this in the past and I have it on my list, but I cannot promise anything soon.
A workaround is to export the JPEG in RAW Power, but tell it to add the exported image back to the library (this is a feature in the app already). Then delete the R+J pair. You can add the exported image to any album you wish, so you can keep them separated while you do this. You can also perform the export as a batch to do all of them at once.
Sorry I don’t have a better answer.