Hello,
Tektronix doesn't set a user name and/or password. If the scope is asking for one then the someone set it. We don't have a backdoor to get through. If you can't get in then you will have to re load the OS and firmware. It's messy (I know) but it's the only solution we have. The scope shipped with the recovery OS and firmware.
The TDS6804B went out of production in 2006. We no longer have the replacement OS available for sale.
You could send the scope into service.
Tektronix/Keithley Repair/Calibration:
Web: https://www.tek.com/en/service-quote
Email: rmarequest@tektronix.com
