Steps to edit account id & siteid in registry using "orca editor"

1.Download and install the orca editor from this link -
2.Open the ManageEngineAssetExplorerAgent.msi using orca editor
3.Select the Registry table in the left nav and edit Account id & site id >>. Then choose CustomAction and enter the Server details and save it.(Attached an image for reference)

Query to find Account & Site ID 

select adef.org_id "Account ID",adef.org_name "account",sdef.siteid "Siteid",sdo.name "Site" from sitedefinition sdef left join accountsitemapping asm on asm.siteid=sdef.siteid left join accountdefinition adef on adef.org_id=asm.accountid left join sdorganization sdo on sdo.org_id=sdef.siteid order by 2

4.Now execute ManageEngineAssetExplorerAgent.msi to install Asset explorer agent / Deploy Windows agents through GPO