1 dont empty the recycle bin when you have deleted the files so if anything is wrong you can get them back wait 3 days to make sure its all working then do it.
2 find boot.ini in c:\ right click properties untick read only. The open with notepad edit as described.
3 save it back as the boot.ini



dont forget to copy boot.ini first so we have a backup

You will have to show hidden files to see it. Try another way open control panel then system then advanced then startup and recovery options. Then you can do it two ways
select the right on at the top to set to default you can then set the time to a 5 seconds so you wont really see the startup bit or
hit edit to edit it as above