How do I untether my iOS devices from my Mac

I currently have my iPhone and iPad effectively tethered to my MacBook Air. Both sync with and backup to my MacBook Air (my iPad used to backup to iCloud and then decided not to). I have about 16GB of apps on my MacBook Air which exist there solely to service my iOS devices and I’d like to switch them directly to Apple’s cloud so I can remove the apps and free up that space.

Someone suggested that I just stop syncing the apps with iTunes but all that did was wipe my devices and force me to restore all the apps and settings. There must be a less destructive way to untether my devices from my MacBook Air so they sync their apps directly with the cloud?