Once you place a loan closure request, it is usually processed by the end of the same day.
After processing, the pledged shares are unpledged and credited back to your demat account within 2 working days. You can sell them once they appear as free holdings.
If your securities were pledged from a non-Zerodha demat account, Zerodha Capital issues the unpledge instruction to the DP and processing can take up to 3 working days. A loan closure confirmation email is sent once the process is complete.