How does one remove the action(bolt) from a remington 750 or 7400 for through cleaning or is there a trick to cleaning the entire bolt while still in the receiver?

The easiest way is to just flush it out with a spray cleaner. If it is not too bad one of the cleaners that leaves some powdered lube behind like Hornady's works good.
If the action is really sandy or gungy, I spray it with Breakfree and let it soak for a while, then I flush it out with Gun Scrubber, which takes out all the oil. I repeat this step if necessary until the action is clean and free of debris. Then I spray it with the Hornady or similar. If there any areai I want to oil or grease in the action I do it now.

I do the same for lever actions , pumps etc. Saves wear and tear of taking them down, loosing parts and the HORROR of ASSEMBLE IN REVERSE ORDER.

Thanks NE