"delete as necessary" is a phrase that is correct and usable in written English. You can use it when editing a text to indicate that words, phrases, or sentences should be removed for clarity or better flow of the writing. For example, "We went to the store, stopped by the park, delete as necessary." Aww/eww – delete as necessary.

'As necessary' in a sentence: The task has always been to find a way to get to that, to get to the work, to claw myself to that as necessary.

My newbie-sense is telling me that "just remove files" only scrubs C: and re-installs, while "remove and clean the drive" might sign me up for a lot more recovery work than I'd like, but I'm dumb at this and don't know what these two options actually do.

One can review use of if necessary, as necessary, and when necessary via examples drawn from links at ngrams. Some sets of examples are given below, with a summary after each set. So check all cylinder fins periodically and clean them if necessary. - Townsend