Email lists support standard Windows multi-select for moving, tagging and deleting etc.
Select all (Ctrl A), then right click and select Delete (or Purge [delete forever] from the System Deleted folder).
When deleting multiple emails, these will be logged via History individually.
Further information
Create a Job, PO or Quote from Email
Delete an Incorrect Email Address
Diagnosing Incoming Email Issues
Diagnosing Outbound Email Issues