your question was how to remove a patch its quite easy you might curse yourself when i will tell you because its toooooooo easy.......all you have to do is this..
do all the same procedure like you do when you a ready to patch a new file ....copy the same patch file to FLASH folder
step 1...drag the file to FLASH folder in Far Manager and click copy...
step 2...before clicking flash check the option REMOVE PATCH.....
step 3...now click patch.........