NFL fields missing team logo

Those are the only two. The two mentioned, plus L.A. Coliseum as currently used by the Rams.

The end zones at Metlife can be (somewhat) easily removed so the team logo for the playing team is displayed. But the time and effort to do the same on the center is prohibitive.

For the Panthers, it was apparently such a big deal for Carolina to get the franchise that the owner Jerry Richardson put it there as a way of thanking the NFL. The placement of the shield seems to be his personal decision. In an ESPN Story, he's quoted:

We have the NFL logo on the 50-yard line for reasons we have talked about before -- we want to reemphasize to our fans that this is NFL football and not something else

---

The sources I used probably predated the Rams move to L.A. and did not mention their current (2017) usage of the L.A. Coliseum. I missed that one and as GB11 points out, there's no team logo there.

As the new Los Angeles stadium is also planned to be used by two teams. We'll have to wait for the opening to see if it will be similar to Metlife or if they have something else in mind.

Actually, those aren't the only two. The LA Rams currently have the NFL Shield as the midfield logo at the Coliseum. This is due to the fact that the Rams share the field with the USC football team and the NFL Shield does a better job at covering up the USC logo (Source).

As you can see in the picture attached to this LA Times article, even when the conditions are less than ideal for turning around the field, the USC logo at midfield is the least visible aspect from the previous night's USC game.