Well, I found an easy way to delete my "Destinations" and "Purposes" of my choice! It worked/benefited me, as I also have proof of my mileage, etc in my hardcopy Planner. Anyhow, I just went to my earliest year of using the Mileage Tracker in Quicken (which is only 2017) and clicked Edit to any trip that had a Destination and/or Purpose that I wanted to delete or rename, by just deleting the text and leaving the field blank. After I was done, I went back to my current 2018 mileage tracker to "add" a trip, and the drop-down list showed only the options that I purposely kept. This may not be a good option for everyone, but I just wanted to share.