Johnty ...... there is no "easy" solution I'm afraid. An alternative to draining would be to buy a simple freezing kit to apply to both pipes, then cut off the folded part and blank off permanently.
You can use these as opposed to the compression blanks. Most plumbers carry a few in the toolbox these days, even if they work solely in copper.......
http://www.screwfix.com/p/polyplumb-socket-ends-15mm-pack-of-2/31175
Folded & hammered ends can work well for years. You could simply hold something like a lump hammer under the pipe (as an anvil), than give it another good hammering.
If you can flatten the pipes a bit further back (to stop the flow), then it's an easy job to clean and apply solder to the flattened ends. Capillary action will get the molten solder into the pipe.
Failing all that...... I like Brighty's suggestion. He must have been a Boy Scout at one time. A good idea ;o)