What if an option seller don't do anything on expiry date

For example seller has sold 10000CE and 8000PE and nifty remains around 9000 on the last day of expiry for example 16th April 20.

He has already got the premium from both options(however small)…now does have to do anything to avoid any STT trap or any other penalty or he can simply let it expire (let it go worthless) and just enjoy prremium?

In what circumstance he has reverse his position right on the last day(expiry day) to protect himself from any negative consequenes?

Both the positions expire OTM (Out of the Money), worthless. There won’t be any charges levied in such case. If you’re new to options, learn from Varsity