Ok, first,this is totally untested, so.....

On uses it at the command line:

rmdif directory map startx starty endx endy

Where:
directory = Directory with dif files. If you have a space in the directory name, enclose with quotes

map is the map id (0-3)

startx = x is the starting x location (your case is 5120)
endy = the starting y location (your case is 2304) ;
endx = ending x (your case 6144)
endy = ending y (your case 4096) ;


Now, this will delete the total block (not partials, so if the x,y moves into a map block, the entire map block gets deleted from the dif file.

I didn't think T2a was done with Dif's,but perhaps it is.

The resulting dif files will be labled with an extension ".wfg". You can rename them. Just another check.
This shouldn't need any dll's, and is a command line utility.

MAKE BACKUPS! This has never been run!