Quick and Dirty Solution for Windows
Clean_Win_Reg.cmd
@echo off
setlocal enableextensions enabledelayedexpansion
# Nr of lines deleting from Registry
set len=3
set /a len_pos=%len%-1
# Get the MRUList from Registry and save it to %mru%
for /f "tokens=2*" %%a in ('reg query HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU /v MRUList') do set "mru=%%b"
# Count chars
for /f %%c in ('cmd /u /v /q /c"(echo(!mru!)" ^| find /v "" ^| findstr /r /c:"[a-z]" ^| find /c /v ""') do set "str_len=%%c"
# Get the last Nr of defined lines from MRUList
set list=!mru:~0,%len%!
# Set the new MRUList
set original_list=!mru:~%len%,%str_len%!
# Delete old MRUList
reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU" /v MRUList /f
# Add new MRUList
reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU" /v MRUList /t Reg_Sz /d %original_list%
# Delete the last Nr of lines from Registry
for /l %%d in (0,1,%len_pos%) do (reg delete HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU /v !list:~%%d,1! /f)
PS: You have to take the REG DELETE "Path" in double Quotes
QUACK STRING reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU" /va /f