we can directly delete it via ADSIEDIT:
The location should be: first organization -> CN=Address Lists Container -> CN=Offline Address Book
If you are decommissioing the 2010 server. Will not harm and you will be able to uninstall exchange 2010 gracefully from control panel.
See https://docs.microsoft.com/en-us/Exchange/email-addresses-and-address-books/offline-address-books/oab-procedures?view=exchserver-2019#use-the-exchange-management-shell-to-change-the-organization-mailbox-thats-responsible-for-generating-an-offline-address-book