1-is cholesterol level related to stress and depression?

2-if we reduce the cholesterol level it might cause to reduction in blood sugar?

no. the only way that cholesterol would be related to stress is indirectly. for example if a person had a doctor’s visit and found out that they had a dangerously high cholesterol level it could cause stress and add to depression, but directly there isn’t a relationship between them. Your second question is the same answer. reducing your cholesterol will not reduce your blood sugar directly. the only way it would, would be because of diet changes to reduce the cholesterol. so the answer to both questions is no, not directly, but yes they could indirectly.