Para responder sua pergunta inicial primeiro; você não está seguro apenas reinstalando o Windows, já que não pode garantir que os dados em questão sejam sobrescritos.
Você pode querer substituir os dados confidenciais (excluídos) usando uma das opções disponíveis;
Você pode usar o comando DiskPart - Clean All -, mas certifique-se de saber com qual disco está trabalhando.
Você pode (após excluir os dados confidenciais) usar o comando Criptografia com a opção /W
.
Você também pode criar um arquivo BAT simples ou dois - algumas amostras abaixo;
Um comentário adicional: Se você limpar o disco / dados 2-3 vezes, alterando os padrões magnéticos além do reconhecimento, até mesmo 'pessoas incrivelmente poderosas' não poderão recuperar os dados.
---
@echo off
rem Simple Disk Wipe Utility - wipedfast.bat
rem ---
rem --- 1) Delete all unwanted content from disk, leaving possibly only the command interpreter to run this script.
rem --- 2) Delete content from trashcan/recycled, if any.
rem --- 3) Run this script until it reports file system full.
rem --- 4) Delete WASH*.TMP files on each drive to reclaim space or to rerun utility.
rem --- Do this for all file systems/drives (C:, D:) on system, at least a couple of times.
rem ---
echo Grow file system test (fast / large increments - less secure). See comments in script file.
echo To be done for each drive (C:, D:) on system.
echo Abort with Ctrl-C when disk full and delete WASH-files
echo - Ideally run wipedfast.bat first - then wiped.bat when disk full - before deleting WASH-files.
pause
echo abcdefghijklmnopqrstuvwxyz0987654321ABCDEFGHIJKLMNOPQRSTUVWXYZ > wash_a.tmp
copy wash_a.tmp wash_b.tmp
:start
copy wash_a.tmp+wash_b.tmp wash_c.tmp
del wash_a.tmp
del wash_b.tmp
copy wash_c.tmp wash_a.tmp
ren wash_c.tmp wash_b.tmp
goto start
---
@echo off
rem Simple Disk Wipe Utility - wiped.bat
rem ---
rem --- 1) Delete all unwanted content from disk, leaving possibly only the command interpreter to run this script.
rem --- 2) Delete content from trashcan/recycled, if any.
rem --- 3) Run this script until it reports file system full.
rem --- 4) Delete WASH*.TMP files on each drive to reclaim space or to rerun utility.
rem --- Do this for all file systems/drives (C:, D:) on system, at least a couple of times.
rem ---
echo Wipe file system (slow / small increments - most secure). See comments in script file.
echo To be done for each drive (C:, D:) on system.
echo Abort with Ctrl-C when disk full and delete WASH-files.
echo - Ideally run wipedfast.bat first - then wiped.bat when disk full - before deleting WASH-files.
pause
echo abcdefghijklmnopqrstuvwxyz0987654321ABCDEFGHIJKLMNOPQRSTUVWXYZ > wash_a.tmp
copy wash_a.tmp wash_b.tmp
:start
copy wash_a.tmp+wash_b.tmp wash_c.tmp
del wash_b.tmp
ren wash_c.tmp wash_b.tmp
goto start