The description for watery sphere says:
If [the sphere] moves over a pit, a cliff, or other drop-off, it safely descends until it is hovering 10 feet above the ground. Any creature restrained by the sphere moves with it.
Say I cast this spell on myself or an ally, and they willingly fail their saving throw as stated here:
Any creature in the sphere's space must make a Strength saving throw [...] a Large or smaller creature can choose to fail it.
Then, if I moved them over a cliff, would the sphere gently carry them down until it's 10 feet off the ground? Could I then cancel the spell, causing them to fall just 10 feet instead of however tall the cliff was, and negate the vast majority of falling damage?