How to delete terms in ontology?

Hi,
I've read the documentation quite extensively, yet I haven't found any method or function to delete a term from an ontology.
For example:
```python
from pronto import Ontology
go = Ontology("http://purl.obolibrary.org/obo/go.obo")
```
If I try
```python
del go['GO:0000001']
```
I get:
```python
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
in
----> 1 del go['GO:0000001']

TypeError: 'Ontology' object does not support item deletion
```

Is there any way to achieve item deletion?