Hey @HIREiN,
If in case you do not withdraw/ close your PPF account, it will be extended for 5 more years.
For withdrawal from PPF account you need to submit a withdrawal form to the respective bank/post office. After your application is processed and approved, the amount is credited to the linked bank account or given as a cheque.
Here’s a read that might help you further: What happens to your PPF account post its maturity? We explain | Mint