Q: Is there any way to mass delete or mass inactivate users from Lifecycle?
A: No, you cannot mass delete or mass inactivate users in lifecycle through the UI. If you would like to explore ways to do this using the API/SDK, please start at these articles:
Getting Started with the API
Updating an asset
It is not recommended that you delete a user, as this will remove them from things they have owned in the past. The data is still in the database, but there would be a blank for the owner in reports. Inactivating them will allow them to still show up but they will be struck through so it is obvious they are inactive.