Cancelling, and what happens to your data
Leaving, without leaving your records behind.
Export everything first. Every record type comes out as CSV from Import and export, and that works whether you are staying or going — it is a button, not a retention conversation.
Moving down rather than out
If the issue is cost, moving down a plan keeps everything readable. You can still open every report, ledger and entry you created; you simply cannot add to the parts the smaller plan does not cover.
What residents see
If you close the account, residents lose the portal. Tell them how to pay before that happens rather than after — the first they should hear of it is not a payment failing.