Connect device by IP

Enter these commands in Android device Terminal

su
setprop service.adb.tcp.port 5555
stop adbd
start adbd

After this, you can use CMD and ADB to connect using the following command

adb connect 192.168.0.101.5555

And you can disable it and return ADB to listening on USB with

setprop service.adb.tcp.port -1
stop adbd
start adbd

From a computer, if you have USB access already (no root required)

It is even easier to switch to using Wi-Fi, if you already have USB. From a command line on the computer that has the device connected via USB, issue the commands

adb tcpip 5555
adb connect 192.168.0.101:5555

Replace 192.168.0.101 with device IP