‘Fear’ is a broad term but encompasses feelings such as insecurity, lack if confidence, low self-esteem etc. It is usually the underlying emotion that leads to other negative ones including anger, jealousy, embarrassment, sadness etc.
It is helpful first to identify, acknowledge and accept those things that are making us fearful - do so in a non-judgemental way i.e. this is just the way you feel, it is not your fault and it is likely that anybody else who has had your life experiences would feel the same way too. Tell yourself this is okay. We can then use this as a basis to move forwards from.
Emotions are generally outside of or conscious control, being generated from deeper parts of the brain, the colloquial ‘subconscious mind’. However, we can certainly influence them - this does take time, repetition and perseverance though.
A couple of simple, yet very effective methods are to recite (out loud) a daily positive affirmation. This is a positive, personal statement such as what you like about yourself, what you are going to achieve etc. It doesn’t have to be long and there are lots of examples you can search for, but ideally I would suggest creating your own that is meaningful to you. It may seem banal, but please don’t underestimate how powerful this method is for positively influencing your subconscious processes including self-perception, self-worth, internal dialogue etc.
The second is to keep a ‘gratitude diary’ - ideally a physical notebook on your bedside table. Before you go to sleep every night, write down 3 things that have gone well or you are happy about that day (it doesn’t matter if they are trivial or silly things). Again, this has a strong positive influence on the subconscious and also tends to improve sleep quality too.