If you find that how to delete applications on mac, in most cases, it's because the app keeps running or the system has protected it. Simply, quit the app from the Dock, or you can press Command + Q. If it's not going to close, then you should open Activity Monitor, locate the app, and click Force Quit. After that, go to Finder > Applications and give dragging to Trash a try once again. If the problem of not being able to delete continues, then you should restart your Mac and try one more time. Certain macOS built-in applications cannot be uninstalled because they are essential for the system. Also, you might require administrator permission in order to delete some third-party applications.