Remove 'custom-cpt' from 'custom-cpt/post-title' from custom post types permalinks

Question

Lets say I have this custom post type: 'pt-services'

So, posts will have this kind of urls:

pt-services/post-one  
pt-services/post-two

How is it posible to remove pt-services from the urls? So they look like:

/post-one  
/post-two

I tried what suggested in here but didn't work...

Any thoughts?