Deleting Documents is not Restricted
Anyone with access to a case or outreach can see and delete documents (files uploaded) by default.
New as of September 2023 is the user role permission "Documents - Delete". Site administrators can remove that permission from a user role to prevent deletions.
Removing the "Administer Documents" permission from a user role prevents such users from deleting entire folders, but not individual documents.
There is no log of who deleted documents. (Ref: LS-41289)