Two ways, and the first is immediate.
Your account and its ways of signing in go at once. Your backup is held for 30 days, so signing in the same way within that time brings your wallet back; after that it is erased for good. Categories you shared with other people stay with them, because they are their records too.
The wallet on your own phone is separate: signing out clears it from the device, and uninstalling the app removes it.
Write to support@hemadol.com from the address your account uses, and say you want it deleted. We will confirm once it is done.