Yes, it depends on how you made the dress. If the plane is a separate polygroup it will be easy to get rid of - turn on polyframes (Shift+F) to see. If the plane not a separate polygroup then you could try Tool>Polygroups>Auto Groups. This will make the plane into a separate polygroup if it is a separate object from the dress. Then you can:
- Shift+Ctrl+click on the plane. This will hide everything else.
- Shift+Ctrl+click on the plane again. This will reverse the visibility so the plane is hidden.
- Press Tool>Geometry>Modify Topology>Del Hidden. This will delete the plane.
If the plane is not a separate polygroup or a separate object then it will be more difficult to get rid of. You may be able to use masking to isolate it - you can use Backface masking to help with that but remember you need to hold Ctrl while turning it on. You’ll need to experiment with what works best for the model.