you get the router into rmon and then you should be able to erase and re-partition the flash.
Some info that might help
About bootrom versions which details which ones can partition flash on a 2500 series router
This came from one of the many message threads:
<<<<groupstudy.com>>>>
25xx routers are run-from-flash, which means that one partition is going
to hold an image the router is actively using during operation,
therefore it must be read-only. To get the read-only partition to be read-write, you must boot from
ROM. If the configuration register is 0x2102 (a common setting), you
must change it to 0x2101 to boot from ROM. Then you will be able to
manipulate the flash the way you want. After you get the two partitions combined into one again and have the
IOS image(s) in flash the way you want them, you should change the
configuration register back to 0x2102 (or whatever it needs to be based
on your network). Pamela
<<<<<<end of groupstudy.com>>>>>
MikeS "Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin