Helic

I would like to edit the symbol created during the model extraction step in VeloceWired. However I am unable to do so. Can you please explain how one can edit the symbol?

This is a known issue. In fact it is not a bug just a cadence feature.
The reason is that the the generated symbol is a p-cell and cadence treats them differently than a symbol created as new cell.

A simple workaround is to create an empty symbol view with a different name (e.g. symbol_1)
( Library Manager: File-New Cellview and in the pop-up window choose “Composer-Symbol” in the “tool” field).
Then, in the empty symbol view copy the symbol from the original symbol view. The copied symbol will be fully editable.