Hello,
Tektronix does not have an admin password for the scopes. The TDS5000B has the standard Windows operating system. To reset the forgotten password, you will need to work with your IT team. If they are unable to reset the password, you can run an OS restore. However, an OS restore will delete all of your saved data and will revert your firmware version. To run an OS restore, you will either need the original disks or you will have to send me your serial number and I can check if we have the disks.