For sure one cannot just delete or move the logs manually. Logs are purged automatically after a healthy backup. Another process, one could move the transaction logs to a newer partition create or the newly added hard drive. The process of moving the transaction logs cannot be done manually. One should use the Move-DatabasePath command which dismount the database during the process. There might be folders still present in the previous location, one can simply delete them. If you get a warning on the folders, one should restart the Microsoft Exchange Host Controller service and the Microsoft Exchange Search service. Once this is done, one can run the Get-Mailbox and verify the LogFolderPath of the database.