Is there a way to delete the multiple users in one shot from the model.
No, you can't delete multiple users in one shot from the model but you can change their role to " No Access" through import option either through module or csv.
I can say that functionality to allow multiple users at a time to be removed from a workspace is being worked on.
Only way we've achieved this is loading in a list of users via the import action on the user tab and setting them to 'No Access', then manually deleting them for now! Atleast we can take comfort in knowing that a solution is being worked on by Anaplan!
Just to say, if you did want to mass delete users from models/workspaces, this now available following this weekend's release