If it's a perfectly good bike at that mileage I'd say you'd have to be mad to break it.
Selling in bits can be worth it, but you need the space and time and patience to take it apart and wait for the items to sell. It could be over 6 months before you see a worthwhile return as parts take time to sell, especially items like the frame etc. Then there may be parts that don't sell and you get stuck with them long term. With a sale you work out a price you're happy with and the deal is done, with breaking you simply hope the sum of the parts will make you more money, but it's a punt.
Also if the bike is perfectly fine, seems a massive waste to break a perfectly good bike with such low mileage. I'd only break if it was high mileage and so low value or crash damaged.
Sell it on whole and you have instant money without the hassle.