The software is safe for 99% of users. However, because it can delete registry entries, you should never use "Delete" on system components (the grey items). Smarty 4.10.0 protects critical Windows files by default, but you should still avoid removing anything related to:
Smarty Uninstaller 4.10.0 Full: The Ultimate Guide to Complete Software Removal Smarty Uninstaller 4.10.0 Full
The scan engine is faster and more accurate in locating leftover files 1.2.2. The software is safe for 99% of users