Clear Transform
Mode
Pose Mode
Menu
Pose ‣ Clear Transform
Alt-G, Alt-R, Alt-S
Once you have transformed some bones, if you want to return to their rest position, just clear their transformations.
Location, Rotation, Scale Alt-G, Alt-R, Alt-S
Clears individual transforms.
To clear everything at once.
Reset Unkeyed
Clears the transforms to their keyframe state.
Only Selected
Note that in Envelope visualization, Alt-S does not clear the scale, but rather scales the Distance influence area of the selected bones (also available through the Pose ‣ Scale Envelope Distance menu entry, which is only effective in Envelope visualization, even though it is always available…).