Removing masking/paper from skirting
Your inclination is correct. A straight pull outward could chip the new paint. Your second inclination is also correct. You should carefully cut through the paint at the paper with a sharp utility knife (sometimes called a razor knife). Hold it horizontally, with a very slight downward angle at the join of the molding and paper.

If you have difficulty keeping the blade from rising up the molding, you could use a metal straightedge to protect it.

You may be able to cut it and remove the paper under the molding rather than through it, but if any is left behind, it should not show and will cause no issue.