To stop Google Play Services from updating itself just follow the below directions.
Open Google Play.
Tap the hamburger icon (three horizontal lines) on the top-left.
Tap Auto-update apps.
To disable automatic app updates, select Do not auto-update apps.
That should then stop Google Play Services from updating itself.
It is not safe to uninstall Google Play services.
Google Play Services is built into the android phones operating system and when you uninstall the Google Play Services it can cause your android operating system on your phone or other device to become corrupt.
That could then lead to your android device and operating system becoming inoperable.
The Google Play Services is a system app and is a package of APIs which are things that assist programmers and allow apps to easily communicate with other apps that ensure fewer apps are dependent upon Android OS updates to run.
So while you could uninstall Google Play Services it's not recommended to do so and it can be hard to uninstall it as well.