If you want to see how many bookings No Showed within a particular time frame, you can access this information within your Enquiries page.
Using your filters which are located under the Search bar - add a date range and apply the 'Status' filter as Confirmed, then before downloading the search Make sure the 'Assigned To' filter on the left side of the page is set to 'Assigned to Anyone' before downloading.
Select DOWNLOAD next to the search bar.
Once you download the excel file, within it - Column T is the 'Actual Guests' column.
If the bookings in question have been marked as a No-Show in Collins, then in this column it will appear as '0' (zero). You can filter the list by the bookings marked as '0' and then see a full list of who has No Showed.