Disabling Yubikey 4 OTP

Since I can never remember this:

I don't make use of the Yubikey OTP mode, so I don't want what a former co-worker called "yubidroppings" when I accidentially brush my key.

Short answer: get ykpersonalize and run ./ykpersonalize -m 5, since I only want U2F and CCID modes enabled. Tell it yes twice.