Hi Imran,
The local admin creds are required for ServiceNow to gather most of the information. If have a plan to do a proper discovery and plan to do Servicemapping in a later phase then it's good to have local admin creds.
There is a way to use JEA from Microsoft if your company thinks of local admin as a security issue.
https://docs.servicenow.com/bundle/sandiego-it-operations-management/page/product/discovery/concept/microsoft-jea-discovery.html
From my experience, many clients initially fear to give it but they would have given the local admin creds for some monitoring tools. If that's the case then ServiceNow also can use those creds. In another way, you can limit the access of discovery admin role and admin roled users in the instance for misusing these credentials from the instance.
Regards,
Vivek
