How to update the identity_column value in sql server 2008

Hi Team,

I have identity column based table. In the table i use insert the name as per the requirement and for ID i use to set the identity now i need to update the particular row id.

when i use to trying i'm getting the below error.

Msg 8102, Level 16, State 1, Line 4
Cannot update identity column 'CategoryID'.

Kindly help me out regarding this.

Thanks & Regards,

Ramesh R