There are many methods to remove bad thoughts from your mind, different methods been used by different people.
method always works for me:
Think of a picture of a state of mind that is free of every distractions and heavy thought, feel the calmness that picture concentrate on how your conciousness observing the silence.
By this way you may be able to observe thyself, energies around you just change the picture according your need.
You can also search other methods here on forums, articles, in coven's book of rituals. As well as on google, wikihow etc..