[robespierre]

I'm not a SUN user, nor have direction knowledge...but I'm good at GOOGLE:
...
PROM password for your station isn't stored in PROM OR NVRAM

Be careful of equivocations. The boot code of a computer is sometimes called its "PROM", especially in the SGI world. Sun just called it OpenBoot and most PCs call it "BIOS" or "UEFI".
A PROM device is a specific type of IC (bipolar, non-erasable, and very fast). The boot code "PROM" is not necessarily (in fact almost certainly not) in a PROM!
By the 1980s, EPROM technology was rapidly developing and would be used for almost all firmware storage. In the 1990s this mostly switched over to Flash which is a dense type of EEPROM.
This mostly happened in parallel with a switch from large DIP packages to smaller PLCC and TSOP packages for firmware chips, but some designs held over. For example, the Indigo2 and Indy both use large, DIP40 EPROM chips for firmware, but the SparcStation 5 uses a PLCC32 Flash chip.

The boot parameters are something quite different and are stored in a different location (it wasn't until the 2000s that Flash chips with internal parameter storage were available). Both EEPROM (byte-by-byte erasable, reprogrammable storage) and NVRAM (SRAM with battery backup power) were used to store settings, and computer vendors mixed up the terminology a lot.

The page you quoted from is hopelessly confused on this point. The author appears to believe that he is removing the "PROM" chip but doesn't know what that means.