Do you mean you want to do this on Control hub? Or are you looking to do this through API?
We can only help from API side, and the only way to achieve this is to write your own script to leverage the https://developer.webex.com/docs/api/v1/scim2-user API. There is an "active" field that returns false when the user is deactivated on Control hub. You could iterate through all your org's users to find users who aren't active and delete them. You'd have to send the delete API request on loop for each user though, there isn't any API that bulk deletes users.
