How to deal with name strings in large data sets for ML?
You problem is essentially you have high cardinality in your features, right? This will be relative to your problem, but you can look for mean encodings. Essentially, you will replace names by the mean on target variable, however, this is highly prone to overfitting and you should take care. 

The following two videos will give an excellent explanation: 


https://www.coursera.org/learn/competitive-data-science/lecture/b5Gxv/concept-of-mean-encoding
https://www.coursera.org/learn/competitive-data-science/lecture/LGYQ2/regularization


However, I would also consider taking out sensitive information such as name depending on your application, always think about if the features makes sense.

I hope this helps, any question let a comment.