From cmd.exe prompt, invoke rm.exe -rf C:\strawberry... or whatever the path
start + shutdown + reboot
start + run + regedit, then in regedit ctrl+f and search for strawberry (or strawberryperl_is1), and when you find a key, delete it unless its the %PATH% variable setting
just to make sure, again from cmd.exe prompt, invoke rm.exe -rf C:\strawberry... or whatever the path