If Blender 2.77a has a user-configurable 'turn delete confirmations' on/off setting, it's sure hidden. To be clear: in Object Mode, for instance, when you key X or press the Delete button on a selected object, a confirmation dialog pops up - confirmations slow my work flow.
Two years ago, an answer to this question (Remove Unnecessary Confirmation Popups ... ) said they were removed - so perhaps this feature is still unavailable?
Shift X
based on this answer. $\endgroup$