How do I delete an app on my MacBook Air?

Depends on the type of App.

If it was installed from the Mac App Store, you can simply drag ti to the trash and empty the trash.

If it used an installer, you may need to use its own uninstaller to remove it.

The macOS user guide is always a good source of information for these types of things.

click here ➜ Install and uninstall purchases from the App Store on Mac - Apple Support

and here ➜ Install and uninstall apps from the internet or a disc on Mac - Apple Support

With most apps, drag the app to the trash. These apps have the type “.app”.

With some apps that insinuate themselves into the operating system, hopefully the app provides a removal tool, or provide removal directions. These apps can have various prefixes, but a “.pkg” package installer is a fairly common choice.

Details directly from Apple: Delete or uninstall apps on Mac - Apple Support

If you’re new to using macOS or need a refresher, here is a guide: Mac User Guide - Apple Support

I usually re-read the user guide every few years, both to help recall derails of existing features, and to learn about new features I might have missed.

I’d be cautious about add-on anti-malware apps, add-on cleaner apps, add-on “coffee shop” VPNs, add-on firewall apps, and similar tools. These tools can be a bad trade-off, and various of these can add problems or can be less than easily removable. If at all well.