What does the National Electric Code - NEC - say about socket outlets under a window?

As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed and to advise you what you may be allowed to do yourself. Before you do any work yourself

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.