Question

If earth suddenly stops rotating the value of g at equator would be?
increase or decrease

Answer 1

Without rotation, Earth will not have equatorial bulge and its radius will go to its average radius of 6,371 km. The simplest way to get this answer is to use the notion of centrifugal force. The equatorial g will increase by amount g1 when not rotating and will be equal to polar g. The increase is only 0.34%.

Answer 2

If earth suddenly stops rotating the value of g will not change. Because suppose that the Earth is not spinning then there will be no centrifugal force acting on the object on the earth. If the centrifugal force will be zero then the value of g will neither increase or decrease.
Also there is the reason that the rotation of the earth do not have any effect on the g of the earth.