What's the best type of tape to cover a pin on a connector?
As suggested kapton tape is useful but sometimes can be a bit hard to work with for something so small. (for me anyway)
If its just the one finger pin you need to block and it is temporary you may find something like liquid electrical tape or conformal coating that you can lightly brush on easier to manage. If none of these are available to you, you might could even get by with a dab of fingernail polish.

If its permanent, why not just cut trace.