Custom post type UI – remove slug from url using rewrite?

Hello

I have the same problem as specified in this thread:

https://wordpress.org/support/topic/plugin-custom-post-type-ui-custom-rewrite-slug-none-option-404-error-when-value-entered

Is it now possible to remove the slug from CPT UIs completely? I have had no luck with my rather depressive rewrite rules (using IIS 7.5)