I would suggest trying out Perform Mode. This allows you to customize the onboard footswitches for whatever use you like, included bypassing the individual presets: https://cdn.eventideaudio.com/manuals/h90/1.7.5/content/play-modes/perform.html

You can also use an external controller for this. Determine whether you’d like to use an aux switch or MIDI CC, and setup some global mappings. This is done most easily using H90 Control (see Global Control towards the bottom of the page): https://cdn.eventideaudio.com/manuals/h90/1.7.5/content/h90-control/system.html