I'm on my routers settings and it says delete device, but I'm worried that I won't be able to reconnect it afterwards.
Deleting the device simply removes the device from the list of currently or previously connected devices. If the device is currently on the network, generally it will simply reconnect again within a few seconds of the deletion. This applies both to Ethernet and WiFi connected devices. It might mean that they may get a different local IP address when they reconnect if the device is configured to get its address automatically. Also, if the router has a reserved address for that specific device, that reservation will be cleared out.
As Mark indicated, you can use MAC address filtering, either by creating a black list that stops specific devices connecting, or a white list that defines only those devices that are allowed to connect. MAC address filtering can sometimes be defeated as some network adapters allow a MAC address to be cloned from one that is allowed access.
Changing the router's WiFi pass phrase is the most secure lock out. However, if this is something you want to do regularly, then there is a better way when using WPA or WPA2 encryption. Keep the pass phrase, but change the network name (SSID). You use the pass phrase for your own connection to WiFi, but give others the encryption key instead of the pass phrase. The encryption key is a 64 hexadecimal character string. This can be found using the tools at
The advantage of this approach is that you can set up the alternative SSID as a separate WiFi network on your device. The original pass phrase will work on both networks, but the 64 character key is specific to the one network to which it applies. If you change the pass phrase, but keep the same SSID, then you have to change both the router and your WiFi device's settings. If you change the SSID but keep the pass phrase, it is only the router that needs changing.
I hope this helps.
Deleting the device just removes it from the list of devices that have connected previously or recently. You need to go to Manage Wireless Connections and add the MAC address of the device to the block list. The MAC address should be in that list you saw where you can delete.
Alternatively you can just simply change the password, When you want them back on just give them the new password. Or change it back to the old one so you don't have to keep thinking of new ones if you need to block them frequently.
you can reconnect it when ever you want, if you are looking to block them for a bit then just block the device