space before footnote reference

When you say "space before" you mean space that precedes the footnote reference correct? I ask because there's a "space before" feature in InDesign that adds space above a paragraph. If what you desire is to remove the space that precedes the footnote reference, you can use Find/Change to remove it.

1. Open the Find/Change dialog box by choosing Edit > Find/Change
2. The footnote reference will either have a character style applied to it or will have the superscript format applied to it however you can't search for characters that have superscript applied because the space that precedes the number won't have that format applied. So in the Find/Change dialog box, click on the GREP tab and in the Find What field, type \s(\d+) and in the change to field, type $1. For safe measure, click on the specify attributes to change property and choose either superscript for the position or choose a character style in which to format the footnote reference.
3. Click find then change a few times to ensure that it is doing what you expect, then click change all.