How do I permanently delete CleanMyMac app from my MacBook Air?

Per AI:

Using the Uninstaller 

1. Open CleanMyMac
2. Click Applications in the sidebar
3. Click Scan
4. Click Manage My Applications
5. Go to the Uninstaller category
6. Find and select CleanMyMac
7. Click Uninstall
8. Confirm your action

If that should fail you can use an app like AppCleaner which will find all the remnants.

See this thread:

How do I completely uninstall CleanMyMac … - Apple Community

Uninstall apps on your Mac

Uninstall apps on your Mac - Apple Support (CA)

1. If the app is currently open, quit the app before continuing.
2. To open Launchpad, click it in the Dock or open it from your Applications folder. Or pinch closed with your thumb and three fingers on your trackpad.
3. If you don't see the app in Launchpad, type its name in the search field at the top of Launchpad. If you have more than one page of apps, you can switch pages by clicking the dots at the bottom of the screen, or by swiping right or left with two fingers on your trackpad.
4. Press and hold the Option key, or click and hold any app until the apps jiggle.
5. Click the Delete button next to the app that you want to delete, then click Delete to confirm. The app is deleted immediately.