QSqlTableModel or any other mode freeing memory

I want to free some memory by deleting all data from QSqlTableModel object. How can I achieve this without deleting whole object, because I want to use its filters and other settings afterwards? In other words after deleting if I call select() to get precise same data as before.
ex.

Code:

---

QSqlTableModel model;
model->setTable();
...
filters and blabla
...
model->select(); //original model
model->release(); //this is imagine 
//
//I can see more memory available in TaskBar
//
model->select(); //i have original model again

---

Is there something like this?

I am not sure, but have you checked if clear() is also reseting the filters?