For about 48 hours after you hit delete, nothing has really happened yet. Cancel inside that window and you keep everything. Miss it and the account is gone for good.
Steps
Open Settings → Privacy, select Delete Account, and confirm.
Your account carries on working normally through the window.
Changed your mind? Cancel the deletion before the window closes and everything stays exactly as it was.
Do nothing, and the deletion goes ahead when the window ends.
After the window closes
Your account is removed, along with your wishlists, wishes, reservations, and saved searches. There's no undo, no backup to restore from, and no further emails from Wishpicks. Support can't bring it back once the deadline passes, so if you're having second thoughts, get in touch while there's still time.
Anyone you shared a wishlist with loses access when the lists go, and reservations on those lists are removed too.
Good to know
Wishpicks Plus is billed separately. Review or cancel it before you delete, or you'll be left paying for a plan you can no longer reach.
Stepping away for a while doesn't have to mean deleting. You can change your name and profile, or switch off the optional emails, and leave the account where it is.
Related
"How do I delete my account?"
"How do I change my email or profile name?"
"How do I change my notification and email preferences (and turn off emails)?"