Bench update without ERPNext update


I would like to install updates of bench. But, bench update command also updating ERPNext. Is there anyway to update bench without updating ERPNext.

I don’t think you want to. Frappe framework and ERPNext generally move in sync, though the version numbers might not always be the same (though this used to be the case and I think they’re working back towards it).
As changes in the framework get pushed to their respective branches, ERPNext adapts to those as needed.