Question

if earth will start rotating 17 times more than now now speed than what will be the value of g at equator

Answer 1

The acceleration due to Earth's gravity (at or beyond its surface) is dependent only on its mass and the distance from its centre (of gravity).

The net acceleration at the Equator is the acceleration due to gravity less the acceleration due to rotation. If you increase the rotation speed, you increase the acceleration due to rotation but the acceleration due to gravity is unaffected, so the net acceleration decreases.