By default all the quantity selectors have a range from 0 - 250. You can limit the range:
Example 1: Set the range of the optional quantity selector for your 2nd upsell item to 0-4:
#optextra2 option:nth-child(n+6){display:none;}
Example 2: Set the range of the optional quantity selector for your 5th upsell item to 0-20:
#optextra5 option:nth-child(n+22){display:none;}
=== Remove Check-in / Check-out selector ===