You are right: God doesn't want our minds to be filled with bad or evil thoughts, no matter what they are. This is why the Bible says, "Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind" (Romans 12:2).
I'm not a psychologist, of course -- but I wonder if you've ever asked yourself why you have these thoughts. I suspect one reason may be hidden anger, or perhaps jealousy and resentment toward other people. There may be many reasons for this (even things that happened in your childhood) -- but face these honestly and turn them over to God for His cleansing and healing. The Bible warns, "Resentment kills a fool, and envy slays the simple" (Job 5:2). Don't let this happen to you.
The most important thing you can do, however, is to open your heart and life to Jesus Christ. God loves you, and He does not want you to be enslaved by evil of any kind -- including these thoughts. Confess your sins to Christ and ask Him to cleanse you and come into your life and transform you.
Then ask Christ to fill you with His love -- His love for you, and His love for other people. Love and hatred cannot exist in our hearts at the same time -- and God's love is stronger than anger or hate. The Bible says, "Love each other deeply, because love covers over a multitude of sins" (1 Peter 4:8).