If I delete drop down options from lists like Reasons for Euthanasia, will data be lost? Can I still report on them? What if I Edit instead of deleting?

Deleting options from drop down lists such as Reasons for Euthanasia, Reasons for Surrender etc only marks the items as Inactive, it doesn't truly delete them. 

This means that users cannot select the reason on an animal's file once the change has been made, but if an animal already has this reason selected it will continue to show on their Animal Details page.

Many of these lists have an "undelete" option so you can reactivate them in future if you need to, or if you deleted them by mistake.  You do not need to "undelete" an item to report on it: simply ensure the option for "all" reasons is selected and the report will automatically include deleted reason as well as current ones. 

Editing an item from one of these lists will mean that all animals will have the new name automatically and any reports (historical or current) will display only the new name.