Freeing your mind makes me think of some sort of enlightenment. However there's a specific practice I use if you mean to literally free your mind from your physical body. I call it mental projection, it's a form of astral travel or venture.
I refer to the subtle body theory to explain mental projection...
Mental Body/Concrete Mind
Something to keep in mind, that I doubt I've mentioned is that the Abstract Mind, or sub-conscience does not project on its own; it needs to hitch a ride with the Mental Body (surfaced conscience) and vice versa.
And of course your physical body can not astrally project at all. Some will claim it can, but the reason it's called a Physical Body is because it exists exclusively on the Physical Plane.
Now then, Mental Projection is often what people refer to as Astral Projecting while their body is fully awake and aware. And most of the people here that claim to do it without actually having to try, are full of bologna. Now Astral Projection can happen while one sleeps without having to try, but Mental Projection is something you must give a tad bit effort into; although it is still achievable while you don't really notice what's happening.
Mental Projection is similar to the concept of throwing your conscience, often achieved through ''day dreaming''. The process is a simplified form of Astral Projection (generally with less steps) and is typically easier.
While one may sit, stand, or lie down, stare off into your mind. Let yourself begin to day dream, but free your mind to do, and see what it wonders to first.
In other words, relax while keeping yourself awake.
With Mental Projection, both your Abstract and Concrete Minds (making up your entire conscience) project.
Once you are completely relaxed, and trying to use as little visualization as possible (visualization will engaged your conscience and you will find it more so difficult to project) attempt to push your actually sight further and try to attach it something solid like a wall or door (this will help keep it from snapping back while you get used to being out of your head).
Your body may feel numb, which is normal.
As you get settled on your wall, or whatever the solid object is, you will need to start concentrating.
Remember, NO VISUALIZATION! You need to see only what is actually there.
Concentrate on finding solid ground, form your Mental Body by recalling how it feels to stand and so forth.
Use what feels like legs to stand up and anchor yourself outside of your Physical Body.