Remove First line of the Time Slots selection

[gbettant]

On my time slots selection tab the first line is not a time slot, but a line that indicates that you need to select one.
But the customer can select this line (by mistake) and then when i receive the order i have the sentence on the line instead of the time slot

Here is a capture of what i have https://fromsmash.com/Fjddw5~dcg-ct

How to remove this line and have the customer select only the slots?

Thank you