TrashMe can avoid to inadvertently delete important applications. For example, applications that came with your Mac or opened applications where suppression would be partial. In addition, you can protect any application of your choice by adding it to a personal list.
If an application is protected, a small "lock" icon appears to the right of the list. You can quickly disable the protection functions by clicking on the little padlock on the bottom of the sidebar. If however you try to delete a protected application through TrashMe, it will prevent you to do so and warn you.
Open TrashMe Preferences
Go to 'Protection' tab
Check all desired boxes or click the "+" button to select an application to protect (you can also drag and drop to the list)