Currently I'm only able to activate and deactivate a rule or data element. Would be a huge time saver for those of us whose rules and elements are repetitive with only slight alterations.
They haven't 'removed' any features here compared to DTM, since Launch was built from the ground up. They just haven't built the feature in Adobe Launch yet. It's on the roadmap for a feature enhancement, and the last update I heard was a target of "this year."
The copies act like completely new data elements. They should have different names like "DataElementName (Copy)". If you don't need these extra data elements anymore, you must ensure that they are not included in any libraries (check the 'Publishing' section) before you can actually delete the item.
There are a few other feature ideas posted here that may help users identify where data elements are used when they are trying to delete them.