Cancel built on system_prompt

I see the model log, there always have one system prompt:
`
{
  "type": "text",
  "text": "You are a Claude agent, built on Anthropic's Claude Agent SDK.",
  "cache_control": {
    "type": "ephemeral"
  }
}
`
then follow my add system prompt 

`
{
  "type": "text",
  "text": "you are a python expert",
  "cache_control": {
    "type": "ephemeral"
  }
}
`


can I cancel it

