NTLMv1
Like LM Hashes NTLMv1 is a weaker authentication protocol that should be disabled. Windows XP and above are compatible with NTLMv2. You can disable NTLMv1, but you should check if you still have an application still using NTLMv1. For that you can check event viewer on each domain controller.
To disable NTMLv1 through Group Policy set the appropriate options in:
Windows Settings > Security Settings > Local Policies > Security Options > Network security: LAN Manager authentication level