Can’t ‘disconnect’ computer from Domain.

I want to ‘disconnect’ a computer from a ‘domain’. The client box used to be on domain. I had to reinstall the NIC & TCP/IP. When trying to add back to the domain I get error ‘already connected to domain – disconnect first’.

1. I removed the computer from within ServerManger on the server.
2. Reboot server. Check to confirm computer is gone from ServerManger.

Can use Client in a ‘Workgroup’ but can’t re-add to ‘Domain’..

Any Ideas.. This should be pretty easy!