Is it allowed to exit the runway by opposites High Speed Taxiway?
It's not really a regulation question, at least not in the way you think. There's 2 possibilities:


A controlled airfield: in an airfield which has air traffic control all movements require a clearance, if the tower clears an airplane to use a taxiway then that is all that airplane is allowed to do unless there's an emergency of some kind. It would be unusual for ATC to direct an airplane to use a taxiway which has such a tight turn, but there's no reason they wouldn't if it the situation called for it
An uncontrolled airfield: in this situation there's nobody in a tower telling pilots what to do, all movements are at pilots' discretion. Pilots can use any taxiway in any way they please as long as it doesn't put them in potential conflict with another airplane