You can remove the calendar buttons if you prefer to use only the enter date through the input field. You need to put this code in the theme CSS

.date .add-on{
display:none !important;
border:0px !important;
background-color: white !important;}

Note that once you remove the calendar button in one place , it will be automatically removed any part of the Joobi products that uses a calendar since they all use the same views.