In general, if you are not going to physically attach an expression pedal to each of the pedal inputs on the back of the AX8, take the following steps:
1) Navigate to: SETUP->IO->CTRL
2) Change any of the parameters on this page that are configured as "PEDAL 1", "PEDAL 2", "PEDAL 3", or "PEDAL 4" to "NONE".
This way any preset that has controllers attached to modifiers will not track with the pedal inputs. These inputs are pulled HIGH (100%) when no expression pedal is attached. However, this does not completely prevent the possibility that the input will pick up ambient electrical noise. This can cause the input to "wiggle" a little. Depending on how the modifier is configured, this can trigger the auto-engage.
NOTE: The factory presets are provided as examples, and therefore contain examples of how to use controllers and modifiers. Most, if not all, of the factory presets containing a WAH block are attached to and EXTERNAL CONTROLLER (i.e. EXTERNAL 1).