You could use a callibration tool for the Warthog throttle. I found one here and it worked at least for me:
https://www.benchmarksims.org/forum/showthread.php?42178-Can-you-remove-the-Idle-detent-in-the-Warthog-Throttle&p=574766&viewfull=1#post574766
My Warthog throttle axis goes all the way back, even beyond the idle cut off.