This feature is too powerful. *USE AT YOUR OWN RISK*
Currently, the custom controls feature on SmrtPack-Kernel Manager offeres the creation of two different types of controllers, and are
Simply open the app, move to Custom Controls page, click the "plus" icon, select the desired option and simply pick the sysfs path from /sys (or any other) folder using the in-built File Picker.
Click the Pop-Up menu on the right bottom corner of each controller, and select the delete option.