BME is Hopkins's flagship program with an extra application component, so I think you would be allowed to drop out of it to the "regular" majors.
I've heard BME is rough as a premed to maintain a high GPA and get ECs done, but people do it. You must be a pretty strong student to have gotten into Hopkin's BME in the first place, and it's a great undergrad that's giving you financial aid. I'd say to check about the rules for dropping BME, but personally I'd go for it