The only way I know how to disable the AH is to disable the pitch and roll alerts. Go to Setup, Alerts and Warnings, AHRS Alerts.
I had the same thing happen to me. I have the Stratux using Raspberry Pi 2. I upgraded to version v1.5b2. Could not get AHRS to disable otherwise. I found you could move the instrument by touching the top then drag it out of the way but couldn't get rid of it until I disabled alerts. I found that the pitch and roll would not calibrate. Pitch and roll were way out of alignment.
Any previous version prior to 1.5b2 works correctly.