Yes! You can't address this field right in the "Load Source Settings at Startup --- Describe Your Sources Here ---" script (where you can pull some of the popover fields), but you can address it in CSS. Add this towards the end of your theme in DayBack and you'll be all set:
.field-container .allDay {
display: none;
)
If you haven't edited the calendar's theme before, you'll find instructions and more examples here:
http://www.seedcode.com/pmwiki/index.ph ... eMaker.CSSHope that helps,
John