In DHCP Manager, select the Addresses tab.
See How to Start and Stop DHCP Manager for information about DHCP Manager.
Select the IP address's network.
Select one or more IP addresses to mark as unusable.
If you want to mark more than one address as unusable, press the Control key while you click with the mouse to select multiple addresses. You can also press the Shift key while you click to select a block of addresses.
Choose Properties from the Edit menu.
The Address Properties dialog box or the Modify Multiple Address dialog box opens.
If you are modifying one address, select the Lease tab.
Select Address is Unusable.
If you are editing multiple addresses, select Mark All Addresses Unusable.