What's the best way to get RV anti-freeze out of system.

The good news is that the pink stuff you used is non toxic and will eventually become so diluted it will not be noticeable!

I no longer use antifreeze ,I just drain everything and blow the lines out with compressed air!

A compact tire inflator works fine !

I have used the same method to clear our Lawn sprinkler system and drain the water from our home plumbing when taking a winter vacation!