That's what I'm trying to say, the system doesn't beheave different if the message is typed as an error or not. If the system is prompting an error and blocks all fields (for example) you should see if there's a way to disable this behaviour( usually functional or technical config), I don't think changing the message type at webui level will solve your issue. But anyway, can you please try to be more clear explaining us:
The scenario (sales, services, business partner, creation, modify, delete...)
What is triggering the error message?
How the system behaves when the errror is triggered?
How do you want the system behave?
Without this is pretty hard to help you.