You are better with a slightly low oil level than with a slightly high one.
To reduce the oil level, just loosen the oil drain plug (over a pan), and by hand slowly turn the plug until oil leaks out. watch the oil level, and only drain as much as is needed.
High oil levels will cause the crankshaft, connecting rods, and transmission gears to pick up more oil and sling it around in the sump and bottom end of the engine - called windage. Windage will cause the oil to foam and aerate it as it picks up air in the foam. Excessive oil on the bore walls is more work on the oil rings, and can build up on the piston skirts and bottoms.
All of this increases pumping losses, reduces power, and can also cause blown oil seals on the crankcase.