Can I cut this at any length for the end point or do I still need to cut at marked location? I don't want to connect any more lights after the cut.

You need to cut at the Marked cut locYou’ll still need to cut at the marked cut locations on the strip. Even if you don’t plan to attach anything after the cut, LED strips can only be trimmed at the designated cut points. Cutting anywhere else may damage the circuit and prevent the strip from working correctly.