To Suspend an account under your Master Reseller Account you will need to click on the "Edit Sub Resellers" Tab and select the user you would like to susend. Look along the account information to the far right. Click the Tick Box of the account under "Sus" and click "Save". The account will then be suspended.
To Delete an account under your Master Reseller Account you will need to click on the "Edit Sub Resellers" Tab and select the user you would like to Delete. Look along the account information to the far right. Click the Tick Box of the account under "Del" and click "Save". The account will then be Deleted.