Disable syntax checker or close its window

[wsdjeg]

## Expected behavior

Sometimes I won't pay attention to the warnings given by syntax checker.

But I don't know to close it correctly, which is quite annoying.

I want to know how to close it or just disable it **one time** or disable it whenever I want

## Environment Information
- OS: Arch Linux
- vim version: 8.0

## The reproduce ways from Vim starting (Required!)


I hate to see this