You can run such two commands to remove Pinyin IME (so latin would become default):
> adb shell
# mount -rw -o remount /dev/block/mtdblock0 /system
# rm /system/app/PinyinIME.apk
the same, but easier to put into Jenkins:
> adb shell mount -rw -o remount /dev/block/mtdblock0 /system
> adb shell rm /system/app/PinyinIME.apk
You can first check which device is mounted to /system by running
# mount
in adb shell.
If you need to remove another IME - just change a filename in "rm" command.
Note: this will remove Pinyin IME completely. While you're not completely sure - don't do it on real devices as it would be hard to bring that IME back :)