Manual can be deleted by
・Manual owner
・Administrator or sub-administrator of the folder where the manual is located
・Group administrator or sub-administrator (have to be a member of the folder where the manual is located)
Please refer to the following manuals on how to do delete a manual:
▼Delete a manual (Web Browser)
https://teachme.jp/8/manuals/4929582/
▼Delete manual (iOS version)
https://teachme.jp/8/manuals/3204671/
▼Delete manual (Android version)
https://teachme.jp/8/manuals/3204829/
▼Delete manual (Windows Desktop App)
https://teachme.jp/8/manuals/14636549/