Hi Nic!
All Akeeba Backup backup archives are stored in the Output Directory, as set in the Configuration page. By default, that is administrator/components/com_akeeba/backup.
When you use a post-processing engine (like Upload to Amazon S3), there is an option to automatically remove the backup archives after they are transferred. You can also achieve the same thing by using the quota settings in Akeeba Backup. Using either (or both) of those methods you can be sure that the backup directory will never grow too big, as Akeeba Backup will clean it up automatically. I am a developer; by definition, I am lazy; so I have automated this repetitive task ;)
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!