Each slot has three rows on Order: Custom Meal Builder:

• CMB: Option N Title - the column/slot name shown to customers (e.g. Proteins).
• CMB: Option N Active - Show displays the slot, Hide removes it from the builder and from order summaries.
• CMB: Option N Is Required? - Required forces the customer to choose an ingredient with a quantity above zero (a warning shows otherwise); Not Required lets them skip the slot.

The number of slots comes from Custom - Items Counts on the Go Live page (default 4). Be aware the CMB Is Required? drop-down lists Not Required first; pick carefully.