How to remove or install memory MacBook air

By "memory" I assume you mean RAM. You cannot. It is soldered on.

http://www.everymac.com/systems/apple/macbook-air/macbook-air-faq/macbook-air-pr ocessor-ram-limitations-superdrive-capabilities.html#ram

Mac Airs can not be upgraded. They are what they are and that is it.