How to split a directory path in NSIS?

I have specified installed path like this: C:\program Files\test\myapp

InstallDir C:\Program Files\test\myapp

Now i want string like this from variable InstallDir C:\program Files\test

Ie. truncate the myapp string from the directory path.How to achieve this?

Is it possible in NSIS?

Nice.Thaks Yathosho.Its working well.