Why did the Lord Say to kill?

Loyal Encourager:

Why did the Lord give the 10 Commandments not to kill and then told them going into the promised land to kill all the men, women and children?

Pilgrim:

Exodus 20:13 “You shall not murder.”
When a man takes it upon himself to end another life, he has judged that life and takes away something he has neither created ( so it is not his to take ) nor can he restore it ( it is out of his ability to make restitution or restore it ).  When a man does this outside of Gods law and authority ( as provided for in the law by God, ’The avenger of blood’ Numbers 35, Romans 13:4, Romans 13:3, etc. ) with anger, malice or selfish intent. ( 2 Samuel 12:9 ) they do so in disobedience to God, committing murder.  
“Vengeance is Mine, I will repay,” says the Lord ( Romans 12:19 , Romans 9:21).  
God alone is worthy, and will judge. ( 2 Timothy 4:1, Revelation 20:11-15 ) 
The righteous God passes judgement and uses his people on occation to carry out His judgement.  We are not necessary for God to carry out His judgement, think of how God passed judgement on the world in Noah’s time and in Sodom and Gomorrah.  This is to teach us His righteousness and obedience to His laws.  For us to see the evil acts that if we partake in will lead to death, spiritual and physically.
Would it be easy to do an act that your own hand killed someone else for doing?  Would you not know that doing that act yourself, even when no one else was around to catch you, was wrong and deserving of death?
God raised up nations to punish, discipline, correct and teach.
1 Samuel 15
God used Israel to punish Amalek, but Saul was disobedient to the word of God, even though he did almost everything he was told to.  Instead of a righteous act of judgement by God, a warning to all other nations, it ended up looking like a mob that murdered for profit and livestock.
God even raised up evil nations to punish and discipline Israel, Babylon and Israels captivity for 70 years.  Usually every time they began to embrace idolatry and worship other gods or sought selfishness instead of service trading their obedience for desire God stepped in correct.  
The scripture is full of this theme, to God be the glory.
I know this is only a scratch but hopefully it helps direct your study.
In Christian love,Thank you for your hart to know God. 1 Corinthians 8:3 “But if any man love God, the same is known of him.”

Blessed be the Lord God, who alone is righteous