Disable Touchboost not available in EX Kernel Manager following some threads on improving battery life, I want to disable touchboost on my Google Nexus 5. 

I am on: 


MultiROM TWRP
ElementalX N5 Kernel
Android 6.0.1, non CAF


And currently using the EX Kernel Manager to manage my CPU settings.

In this thread:
https://www.reddit.com/r/AndroidQuestions/comments/43cq7h/ex_kernel_manager_no_touchboost/

It says to reflash SuperSU and select "Do not install" when TWRP asks to install SuperSU. The problem is, I can reflash SuperSU, but the "Do not install" option does not come up.

Do I need to completely remove SuperSU to get this option? Thanks.
I don't think it matters. If you install the the correct kernel you should be able to disable touchboast. See my screenshot below.  

Remember if you're updating to a new stock ROM, you can skip flashing TWRP recovery as may be patched on first boot anyway. So you'll need to flash TWRP and SuperSU again after first boot. So after first boot, put your device back into bootloader mode, flash TWRP, reboot the boatloader, then you can boot into recovery and install SuperSU. 

TWRP does not ask to root anymore from my recent experience. I've flashed a Nexus 5, 2 Nexus 5x, and a 6P recently with the most recent version of TWRP, factory ROM with the latest security patch (July) for 6.0.1. 

Again, each time you typically update to a new version of the stock ROM, you need to flash TWRP, then transfer the most recent ZIP of SuperSU to your SD and install from TWRP (make sure you wipe your davik/cache!).  Once you've done this, you can install EX Kernel and then modify your gov, cpu, and turn off touchboast. 

I know you have a Nexus 5 but this post by SlimSnoopOS on XDA will show you everything you need to know on rooting, backups, TWRP, custom roms, kernels, etc. I'd also check out this post by soniCron, regarding the exact task you're trying to complete, which is modifying your gov on your CPU so your battery will last longer. 

Hope this helps.