In The Catcher in the Rye why is holden forgotten to mention is dismissal from percey?

Holden may have omitted mentioning his dismissal from Pencey Prep because he was ashamed or embarrassed by it. He is sensitive about his failures and struggles to fit in, so he may have left out this detail to maintain a certain image of himself in his narrative. Additionally, Holden tends to suppress or ignore negative experiences in an attempt to protect himself emotionally.