If you want to reset the highscore table of ERROR WARE (or other games using Game Maker´s built in high score function), you have to know that the highscore ist not part of the savefile, but its own registry file.
To reset the highscore in Windows open "regedit.exe" (just type it in the windows search bar) and
HKEY_CURRENT_USER\Software\Game Maker\Scores\697783921 (every Game Maker game has its own numbered folder) and delete the "Rank1" to "Rank 10" files. Please don´t delete the "Standart" file!
Then your Highscore table should reset without affecting the savegame.
Have a nice day,
Mc Jey from U-GameZ