How To: Reset the password for an ArcGIS Server local account
By default, when ArcGIS for Server is installed on a client machine, the ArcGIS Server local account 'arcgis' is created. In some instances, the password must be changed. The instructions provided describe how to reset the password for the ArcGIS Server local account.
Click the Windows Start button.
Go to Control Panel > Administrative Tools > Computer Management.
In the left pane of the Computer Management window, expand Local Users and Groups.
Select the Users folder.
Right-click the ‘arcgis’ icon, and click Set Password.
Select Proceed, and enter the new password twice.
The new password for the ArcGIS Server local account 'arcgis' is now updated.