To be able to manage reseller accounts you must:
To manage (Edit, Suspend, Activate or Delete) any reseller account you can do this from the list of accounts.
How to change account owner?
If you want to change the owner of some account to be owned by the reseller you need to edit that account package and set it to be a package of the reseller.
Note: The login as a reseller is done from the end-user panel url https://MYIP:2083