Replacing an asset while keeping meta data tags

I have a large amount of assets that have quite a bit of metadata tags assigned to each one. I am needing to modify each file and re-upload them. Is there a way to do so and keep the metadata tags assigned to the new file? When I try to upload a new version and have it replace the old version it wipes out all the metadata tags. If I upload it and create a version it keeps the metadata intact but then im wasting storage housing an old file i dont want and i cant see how to delete the old version.

Any advice on this would be greatly appreciated!

Thnaks!