The scripture you quoted in your question are Exodus 22:18 and Proverbs 11:21a.
It reads
“Thou shalt not suffer a witch to live.” Exodus 22:18.
“Though hand join in hand, the wicked shall not be unpunished:” Proverbs 11:21a
Let me start by stating that the Bible is divided into two aspect, which is the Old Testament and the New Testament. The Old Testament was primarily for the Jews who where under the Laws and the Prophets like Moses, Elijah and the rest.
The coming of Christ Jesus gave rise to the New Testament where we belong. We as believers are not under the old Jewish religion which was govern by the Old Testament. We are believers, under the New Testament which is under the authority and the finished work of Christ on the cross. Thus, Christ is our Master, Lord and Examples.
So, because we are under the authority of Jesus Christ, we take direct instruction from Him, not Moses or Elijah. So, if Moses says something and Jesus counter that instruction with a new instruction, we has followers of Christ (not Moses) will have to follow the new Instruction form Jesus. Except you are under the lordship of Moses.
Moses through God’s leading gave the instruction that “suffer not a witch to live”. Who is a witch? Is a human being who is possessed with an evil spirit to do havoc. Right? And a witch is an enemy of every good thing and everybody.
So, Jesus’ new instruction is not to kill your enemy the witch, but to love them and pray for their salvation.
Matthew 5:38-48.
38 Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth:
39 But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.
40 And if any man will sue thee at the law, and take away thy coat, let him have thy cloke also.
41 And whosoever shall compel thee to go a mile, go with him twain.
42 Give to him that asketh thee, and from him that would borrow of thee turn not thou away.
43 Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy.
44 But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
45 That ye may be the children of your Father which is in heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust.
46 For if ye love them which love you, what reward have ye? do not even the publicans the same?
47 And if ye salute your brethren only, what do ye more than others? do not even the publicans so?
48 Be ye therefore perfect, even as your Father which is in heaven is perfect.
If anyone insist on praying against and kill witches, then you should do it physically, because that was how they were doing it then.
Besides, if we must apply Exodus 22:18, then we should also kill idol worshipers as stated in verse 20, and also apply all the ceremonial and judicial laws in that same Exodus 22. Because there is no room for selective application of the scripture.
The wicked will definitely not go unpublished either in this life or in the life to come. Because in this life the law and justice will catch up with the wicked. Take for example, when an arm robber is caught, he is punished (in whatever way) for it by the law of the land. And in the life to come, if the wicked did not repent, he or she will spend eternity in hell.
I hope I helped you.
I am still open to any clarity you might have either on this subject or on another biblical subject.
Shalom.