files:write scope
This scope lets an app  Upload, edit, and delete files as your slack app
For new Slack apps, files:write replaces both files:write:user and files:write:bot. Here's a bit more detail on why perspectival scopes are disappearing.
This scope is compatible with the following list of Web API methods:
Methods
files.comments.delete- Deletes an existing comment on a file.files.delete- Deletes a file.files.revokePublicURL- Revokes public/external sharing access for a filefiles.sharedPublicURL- Enables a file for public/external sharing.files.upload- Uploads or creates a file.
For some scopes, this list may be incomplete.