Use Clean Up Conversation to tidy up your email conversations and reduce the number of messages in your inbox.
Select an email conversation that you'd like to clean up.
(On the simplified ribbon) On the Home tab, select the arrow next to Delete > Clean Up Conversation. You can also clean up entire Folders.
(On the classic ribbon) On the Home tab, select Clean Up > Clean up Conversation.
If prompted, confirm by selecting Clean Up.
And the emails are sent to the Deleted Items.