I have 1995 honda passport that has a problem disengaging the 4wd to 2wd. I have searched a bit about the similar problem, but they seemed to have a button for switching 4wd to 2wd.

I have a lever (shifter), next to my automatic shifter selector, for switching between 4wd H and L and 2wd H. I noticed that I can easily move the lever between 4wd H and L when the transmission is in neutral or park. I manage to disengage 4wd yesterday when I was experimenting. I had the gear in Drive, and was slowly moving the car. at that point I switched the lever to 4wd and 2wd, and the lever moved without resistance so I thought I was doing it wrong, but I took the car to a muddy road and had the 4wd L and play around for 30 mins then I had the same problem again. I drove for 2 hours or so on highway hoping that hub or whatever is locking would come loose that I can switch from 4wd to 2wd.

does my car have 2 vacuum hose like others have even I have the manual lever?
Should I be able to switch between 4wd to 2wd when moving or do I need to stop?

Thanks for your help in advance!

Your truck does not have the vacuum actuator. You should have locking hubs on your wheels. They are auto lockers from the factory but when they fail most people opt for manual locking hubs. In my 94 I would come to a stop and shift the lever, maybe letting it coast a tiny bit in neutral and it would shift without problems. When shifting out of 4wd with auto locking hubs, you need to backup a few yards to unlock the hubs. When they get old, they don't always like to unlock fully.