Can we omit 'ne' when we use 'plus' ? For example, 'je sais plus' means 'I don't know anymore'?

Bonjour Michael,
As Aurélie points out in the lesson, the «ne» is typically dropped during verbal discourse but not in written language. To my knowledge, this holds true with all of the negation structures. This is in the informal or familiar register of French. Written French is considered more formal register, the only exception being with textos, emails and tweets. However, if one does these, it is certainly not considered improper to include «le ne».