How Do I Block Device from Connecting to My RAX 50?

https://www.downloads.netgear.com/files/GDC/RAX50/RAX50_UM_EN.pdf does clearly state 

"Network access control list
You can use the network access control list (ACL) on the router to block or allow access
to your network and the Internet. The ACL identifies a WiFi or wired device by its MAC
address. The router detects the MAC addresses of the devices on the network and either
allows or denies access.
The router detects and stores the MAC addresses of devices that connect to the network,
so it lists the MAC addresses both of devices that are currently connected and any that
were previously connected.
If you set up a network ACL that allows all new devices to connect, the following applies:
• You can either select or manually enter devices that you want to block from
connecting to the network.
• All other devices are allowed access to the network.
If you set up a network ACL that blocks all new devices from connecting, the following
applies:
• You can either select or manually enter devices that you want to allow access to the
network.
• Devices that are currently connected to the network or that were allowed to connect
in the past are automatically placed on the network ACL as allowed devices.
• All other devices are denied access to the network."

FMI. p.43 ff. on the document above.