Remotely disable Macbook Air through network access
If you had logged in iCloud in your computer you can trace it with that by logging on iCloud.com and then in the find my iPhone tab there you can Do any of the three options, 


Show a message on the screen,
Remotely lock the computer
Clear the data from the computer.


P.S. In any case there is rare chance you may get it back so at the end you have to "forget it"