Hi @VinodC - you would need to implement these requirements with a custom plugin to hide certain buttons/accounts from the UI, or create a new custom QuickLink/Form to handle these requirements for the Service Desk team.
There are some OOTB Manage Accounts action settings for Delete, Disable, Enable, and Unlock, but they are global and would not let you restrict Delete only for the Service Desk team or limit them to seeing only Active Directory accounts. These are found in Gear > Lifecycle Manager.
OOTB DynamicScope options allow you to set what members can request and remove for roles, applications, and entitlements, but this only applies to the Request Access process, not Manage Accounts.
If you end up going the custom plugin route, this pre-built plugin may handle your requirement or be a good starting point to tweak: Remove "Delete" and "Disable" button from manage Account page - #3 by PoojaSingh03