With a non b can you use an existing 90 day non b to work for another employer when you leave the existing one, and then apply for a new work permit?
TLDR : Answer Summary
If you have a Non-B visa that is not company-specific (i.e., it does not list your previous employer), you can change employers and apply for a new work permit. However, if the Non-B visa is company-specific, you will need to obtain a new visa to switch employers.