How to disable HSTS on the management interface ?

Is your management interface internet facing? (I ask this as you mentioned the wifi-hotspot intercept. We jumpbox ours so the management interface is never hit first, prior to logon, even through a hotspot.) I would not recommend disabling the feature.

Perhaps as an alternative if you do lots of work with Fiddler, is to not use Fiddler with the same browser as you use for managing your BIG-IP. Personally I've not seen this particular problem in action.