Deleting a model sounds very dramatic. In fact, it simply means deleting the model information from the Share3D dashboard.
From the models homepage, select a model. You will see that there is an option to "delete model" displayed on the top right hand side of the screen.
If you click on the "delete model" button a pop-up message will appear to ask if you are sure. Click on delete if you want to proceed.
This will delete the model information from Share3D. If you later decide that you want to re-import the model (or perhaps a new version of the model), simply click on "add new model".