You can configure ND to stop sending router advertisements on the IPv6 interface. By default, router advertisements are sent on the IPv6 interface. The ipv6 nd ra suppress command stops the sending of router advertisements on the IPv6 interface.
This example suppresses the sending of router advertisements on VLAN 50:
System(su-config)->interface vlan 50 System(su-config-intf-vlan.0.50)->ipv6 nd ra suppress System(su-config-intf-vlan.0.50)->