1. Should it be an ethical mandate for science to remove a whole section of God’s creation from the face of the earth (for example, the total elimination of certain harmful parasites, germs and viruses)?
The premise should be rejected at the start. Science cannot and will not be able to eliminate anything from the face of the earth unless God allows it. McCall also fails to state what he defines as harmful. Also what ethical criteria is he using? If there is no God, then why would it be ethical to work against natural selection and evolution?
2. If no (to protect theism), should humanity be left to suffer with these divine creations as the Will of God to protect religion?
How does not eliminating harmful parasites, germs, and viruses protect theism? McCall also seems to assume he knows what the Will of God in this is while he has no clue. Guess he did not understand the Bible.
3. If yes, then should the logical next step be to eliminate God (Theism itself) as an ethical failure due to the fact that science is having to cleanup up God’s many malevolent creations?
Given that neither the first nor second "questions" are logical, it makes no sense to assert malevolence on God's part in any way. Let's let Apostle Paul help McCall out with the reason why the created order is the way it is now.
God has not eliminated the pains and suffering in this life (all due to sin) because God is waiting for all those who will be saved to be actualized. Clear now? You're Welcome, Mr McCall.
18 I consider that our present sufferings are not worth comparing with the glory that will be revealed in us. 19 For the creation waits in eager expectation for the children of God to be revealed. 20 For the creation was subjected to frustration, not by its own choice, but by the will of the one who subjected it, in hope 21 that[h] the creation itself will be liberated from its bondage to decay and brought into the freedom and glory of the children of God.
22 We know that the whole creation has been groaning as in the pains of childbirth right up to the present time. 23 Not only so, but we ourselves, who have the firstfruits of the Spirit, groan inwardly as we wait eagerly for our adoption to sonship, the redemption of our bodies. 24 For in this hope we were saved. But hope that is seen is no hope at all. Who hopes for what they already have? 25 But if we hope for what we do not yet have, we wait for it patiently.
26 In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us through wordless groans. 27 And he who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for God’s people in accordance with the will of God.
28 And we know that in all things God works for the good of those who love him, who[i] have been called according to his purpose. 29 For those God foreknew he also predestined to be conformed to the image of his Son, that he might be the firstborn among many brothers and sisters. 30 And those he predestined, he also called; those he called, he also justified; those he justified, he also glorified. - Romans 8: 18-30
Debunking Christianity: Three Questions Concerning the Function of Theism in the Modern World