My model is not displaying properly and I would like to remove it from the library.
Hover over your profile avatar (upper right), click into "my models", select a model, then "edit model" to be able to delete them.
Rather than delete it, it might be easier/better to upload an image file. The image file is used by the gallery, and it is the default view of your model that everyone sees.
Providing a really nice rendered image of the model will likely boost the likelihood of it being downloaded and liked.