There are a few ways to deal with this. You can purchase a replacement PN2907 transistor, then cut the one off that's on there now but cut it so that as much of each lead is left sticking up out of the board as possible, then heat up each pad and slip the lead out, then install the new transistor.
You could also attempt to use solder wick, a spring loaded desolder pump, or an electric vacuum desoldering tool to remove the solder that's there, then turn the transistor around and solder it back in. The PN2907 should still work just fine.
If someone else built this, I would send it back.
