Telegex.delete_chat_photo

You're seeing just the function delete_chat_photo, go back to Telegex module for more information.
Link to this function

delete_chat_photo(chat_id)

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Specs

delete_chat_photo(integer() | String.t()) ::
  {:ok, boolean()} | {:error, Telegex.Model.errors()}

Use this method to delete a chat photo. Photos can't be changed for private chats. The bot must be an administrator in the chat for this to work and must have the appropriate admin rights. Returns True on success.