Archive it and move on with my life.
The work is generally entangled per the terms of your contract. If you want to do anything particular with it, the contract needs to cover that.
Specific things you may be thinking of:
* Showing off "portfolio samples" based on incomplete work - this is apt to annoy clients if you're not careful with it, and any given portfolio sample is unlikely to make or break your ability to land clients. If you think it might, you need to take a hard look at your sales process.
* Code reuse - this should be something your contract already covers for all projects. This code is mine, I am licensing this particular configuration of it for you to use based on specific terms, and assuming that you complete your end of the contract (i.e. pay me).
