Confirm what they want
Read the request carefully. Some customers want to pause, switch plan or stop a single product, not leave entirely.
Ask why, once
Offer a short question or a choice of reasons. One question is useful; a long interrogation feels like a trap.
Offer an alternative that fits
If price is the problem, show a cheaper plan. If they are busy, offer a pause. Only offer what you would accept in their place.
Make leaving easy
Complete the cancellation promptly when they confirm, and send a clear note with the end date and what happens to their data.
Leave the door open
Tell them how to come back and keep their data for a stated period. Many customers return when their situation changes.
Tag every reason
Review the reasons each month. A pattern in price, missing features or support quality tells you more than any survey.