Value Adjustment Posting in Asset

Hello All ,

We need to reduce the value from Value adjustment in Asset .. what is the process ?

Fox example , in Value adjustment is is 1,00,000  we need to reduce it to 80,000

@Moderators - I did a lot of search around this found below link but nohting helps  hence posting new query
my problem is bit unique

http://scn.sap.com/thread/1824072

http://scn.sap.com/thread/372095

http://scn.sap.com/thread/1685244

http://scn.sap.com/thread/1481506

http://scn.sap.com/thread/3581327

Thanks

Aryan