I want to delete all bin and obj folders to force all projects to rebuild everything

This depends on the shell you prefer to use.

If you are using the cmd shell on Windows then the following should work:

FOR /F "tokens=*" %%G IN ('DIR /B /AD /S bin') DO RMDIR /S /Q "%%G"
FOR /F "tokens=*" %%G IN ('DIR /B /AD /S obj') DO RMDIR /S /Q "%%G"

If you are using a bash or zsh type shell (such as git bash or babun on Windows or most Linux / OS X shells) then this is a much nicer, more succinct way to do what you want:

find . -iname "bin" | xargs rm -rf
find . -iname "obj" | xargs rm -rf

and this can be reduced to one line with an OR:

find . -iname "bin" -o -iname "obj" | xargs rm -rf

Note that if your directories of filenames contain spaces or quotes, find will send those entries as-is, which xargs may split into multiple entries. If your shell supports them, -print0 and -0 will work around this short-coming, so the above examples become:

find . -iname "bin" -print0 | xargs -0 rm -rf
find . -iname "obj" -print0 | xargs -0 rm -rf

and:

find . -iname "bin" -o -iname "obj" -print0 | xargs -0 rm -rf

If you are using Powershell then you can use this:

Get-ChildItem .\ -include bin,obj -Recurse | foreach ($_) { remove-item $_.fullname -Force -Recurse }

as seen in Robert H's answer below - just make sure you give him credit for the powershell answer rather than me if you choose to up-vote anything :)

It would of course be wise to run whatever command you choose somewhere safe first to test it!

I found this thread and got bingo. A little more searching turned up this power shell script:

Get-ChildItem .\ -include bin,obj -Recurse | ForEach-Object ($_) { Remove-Item $_.FullName -Force -Recurse }

I thought I'd share, considering that I did not find the answer when I was looking here.

This worked for me:

for /d /r . %%d in (bin,obj) do @if exist "%%d" rd /s/q "%%d"

Based on this answer on superuser.com