Well, you can go to the appropriate directory and delete the pretenders manually, but that's kind of ugly, _especially_ considering that the files are named things like "late_tienchi_1.2h", "late_tienchi.2.h", etc. Which gets even uglier when you have to find/send the pretender file for a PBEM game.
Frankly though, the best hope for a pretender viewer is for one of the community's programmers to write a stand-alone tool for it - Illwinter doesn't like to program non-fun things, and besides I think we _want_ them working on gameplay stuff instead.
But a file format for the pretender files would certainly be handy.