@user29381 

A TP-Link ID, used to connect devices to cloud features, such as Kasa, Deco, and online updates is associated with an Email account.  This email address will be the Username of the account being used.  You can create a new account using a different Email address if you want but you cannot set a Username other than the email address itself. 

But, I'm not talking about changing the username on my tplink account. I want to be able to access my wifi router admin without the tplink account. I don't need any of those cloud services.

With the router admin dependent on the tplink account, my security is only as good as the security of tplink. If someone hacks the tplink cloud, and from there hacks into my account, then they have access to my network.

@user29381 

All you will need to do is to disassociate your router with the TP-Link Cloud. What will happen is the login name will revert back to the default user name which is admin.

Log into the router go to Basic > TP-Link Cloud > Click on "Unbind".

To change the default login name and password, you would go to Advanced > System Tools > Administration.

Thank you. That's what I wanted to know.

@user29381