How can I curse those God has not cursed?

“How can I curse those God has not cursed? Or how can I [violently] denounce those the Lord has not denounced? For from the top of the rocks, I see Israel, and from the hills, I behold him. Behold, the people [of Israel] shall dwell alone and shall not be reckoned and esteemed among the nations.  Who can count the dust (the descendants) of Jacob and the number of the fourth part of Israel? Let me die the death of the righteous [those who are upright and in right standing with God], and let my last end be like theirs!” Numbers 23:8-10 (AMPC)

Nobody can change your destiny.
No one can destroy your purposeful life’s assignment.
Only the Counsel of God shall come to pass in your life 
When you have indeed given your life to Christ, and daily walk in His obedience, you are unstoppable.
 Balaam could not curse the people of Israel that God has Blessed.
You are the righteousness of God in Christ Jesus.
Don’t allow the fear of the enemy to creep into you that someone somewhere has pronounced a curse upon you.
Walk with the Spirit of Courage and Sound mind that God has given you.
“Only you be strong and very courageous, that you may do according to all the law which Moses My servant commanded you. Turn not from it to the right hand or to the left, that you may prosper wherever you go.” Joshua 1:7(AMPC)
Do not say any negative thing with your mouth concerning yourself and all that God has blessed you with. 
“No weapon formed against you shall prosper, And every tongue which rises against you in judgment You shall condemn. This is the heritage of the servants of the LORD, And their righteousness is from Me,” Says the LORD.” 
Isaiah 54:17 (NKJV)
Flee, Run, and distance your self from every sinful and compromising life.
No Curse can come upon as you walk in obedience to God. 
Repent and completely turn away from sin and stay blessed and fruitful in what God has purposed for you.