Download KernelSU Manager from (Download the artifact named manager).
manager
Unzip the downloaded zip package and get the manager apk named KernelSU_vx.x.x-xx-.....apk.
KernelSU_vx.x.x-xx-.....apk
Use the command adb install <apkname>.apk to install the manager.
adb install <apkname>.apk
Download pre-build kernel from (Remember to download the same architecture).
Unzip the downloaded zip package and get the kernel file named bzImage.
bzImage
Replace the kernel in the folder named Tools in the WSA directory with bzImage.
Tools
Restart WSA and then enjoy.