Changing user permissions

[Bob Graham]

I have a problem with wanting to deny users delete priveleges on a group of
folders and files. The files are Excel files.

My program code opens the files and allows users to make changes and then
saves the files. However, because of the way Excel saves files, if your
users have "Deny Delete" on the files in question, this generates garbage
files that accumulate into gigabytes.

Ref: http://support.microsoft.com/kb/814068/

My question is, is there a way to add the user to a group that has Allow
priveleges temporarily and then remove them from that group when my code is
done executing?

Thanks in advance

Bob Graham